Review

Significance of anti-HBc alone serological status in clinical

practice
Qixia Wang, Paul Klenerman, Nasser Semmo

Serum samples identified as positive for total anti-HBc, but negative for both HBsAg and anti-HBs, are referred to Lancet Gastroenterol Hepatol
as anti-HBc alone. This serological response is compatible with acute, resolved, and chronic hepatitis B virus (HBV) 2017; 2: 123–34

infection but might also signify occult HBV infection. Once the anti-HBc alone pattern is detected, false-positive Division of Gastroenterology
and Hepatology and Shanghai
reactivity should be ruled out and further analyses can resolve the clinical status of the donor. The identification of
Institute of Digestive Disease,
anti-HBc positivity in the absence of HBsAg in organ transplant donors and in candidate patients for chemotherapy Renji Hospital, Shanghai Jiao
and immunosuppressive therapy requires further investigation because of the risk of HBV reactivation. False-positive Tong University, Shanghai,
detection, acute infection during the window phase, and resolved or chronic HBV infection are all possible and only China (Q Wang MD);
Hepatology, Department of
distinguishable if the additional assays are done and measures of liver damage are taken into account. Measurement Clinical Research (Q Wang,
of serum anti-HBs responses after the administration of HBV vaccination can be useful to distinguish this serological N Semmo MD) and University
profile. In view of the low risk of HBV reactivation in anti-HBc alone patients who are candidates for Clinic of Visceral Surgery and
immunosuppressive treatment, such patients might not require pre-emptive antiviral therapy, but should be Medicine, Department of
Hepatology (N Semmo),
followed up on a monthly basis for alanine aminotransferase followed by quantitative HBV DNA testing in those University of Bern, Bern,
with alanine aminotransferase increase. According to specific guidelines, nucleoside analogue prophylaxis is Switzerland; and NIHR
recommended in anti-HBc-positive liver allograft recipients and anti-HBc alone individuals who receive Biomedical Research Centre,
chemotherapy or biological therapy and should be continued for 6–12 months after discontinuation of such Translational Gastroenterology
Unit (Prof P Klenerman FMedSci)
immunosuppressive therapies to protect against HBV reactivation. and Peter Medarwar Building
for Pathogen Research
Introduction arises in diverse clinical risk groups (eg, intravenous drug (Prof P Klenerman), University
Hepatitis B virus (HBV) infection remains an important abusers, hepatitis C virus [HCV] and patients coinfected of Oxford, Oxford, UK

disease worldwide. This infection can be either acute with HIV, patients with haemodialysis, recipients of Correspondence to:
Dr Nasser Semmo, Hepatology,
or chronic, and can range in severity from being organ transplants, and pregnant women).7–12 Department of Clinical Research,
asymptomatic and completely resolving, to severe and For the purpose of this Review, five possibilities University of Bern,
symptomatic with progressive, potentially fatal disease.1 and clinical courses of anti-HBc alone are discussed Murtenstrasse 35, CH-3010 Bern,
HBV has an outer envelope component of hepatitis B (figures 2, 3). Switzerland
nasser.semmo@insel.ch
surface antigen (HBsAg) and an inner nucleocapsid
component of hepatitis B core antigen (HBcAg). HBcAg False-positive reactivity
can be detected in the liver, usually in the nucleus or Serum HBsAg, anti-HBs, HBeAg, anti-HBe, and HBV
cytoplasm of hepatocytes, but not in serum. Core epitopes DNA when relevant, should be assessed in patients
of HBV are a potent immunogen. During natural HBV at risk. A positive result, and especially detectable
infection, they induce a cellular and humoral immune circulating HBV DNA, could provide important
response manifested in T-cell proliferation and also induce information with practical implications in patients with
production of high anti-HBc titres.2 Hepatitis B e antigen overt or occult chronic HBV infection. Although modern
(HBeAg) is found as a soluble protein in the blood of HBV immunoassays for anti-HBc are highly specific, washing
carriers and is associated with the degree of viral replication. errors and instrument failures can occur, and serum
Anti-HBe antibodies might be detectable regardless of samples could be mixed up or contaminated. This
the presence or absence of HBsAg or anti-HBs, but not possibility should be excluded by a repeated assay of
without anti-HBc. Testing for anti-HBe can offer additional anti-HBc, and a second serum sample should be
information to that provided by anti-HBc in cases of requested if an individual has been found anti-HBc alone
chronic hepatitis. Thus, the terms anti-HBc alone or for the first time. If anti-HBc is repeatedly positive, but all
isolated anti-HBc positivity is referred to regardless of the other assays are negative, the specificity of the anti-HBc
anti-HBe status. Since anti-HBc is present during different reaction should ideally be checked by an assay from a
phases of HBV infection, testing for anti-HBe could different manufacturer. Although radioimmunoassay has
occasionally be indicated only when anti-HBc is positive been shown to be more specific for anti-HBc detection
and HBV DNA is undetectable by a sensitive PCR assay. than enzyme immunoassay, radioimmunoassay is not
Figure 1 shows the different evolutions after HBV exposure. currently used in most clinical laboratories, which mainly
The proportion of individuals with anti-HBc as the use enzyme immunoassay technology for this purpose.
only positive HBV serum marker has been reported The presence of anti-HBc in the absence of anti-HBs and
in different populations ranging between 1% and 32%.3–6 HBsAg could signify a false-positive result related to
However, although common, individuals with anti-HBc method specificity, particularly when testing is done by
alone who seek medical advice are faced with uncertainty enzyme immunoassay.5,13–18 Parkinson and colleagues19
about the clinical significance of this test. This situation compared these two methods and found that most serum

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 Review

incubation, and washing protocols could contribute to

A
false-positive results.
HBV DNA
Although there is a WHO standard for anti-HBc
allowing labs to quantify concentrations of antibodies,
HBeAg Anti-HBe there is no licensed or FDA approved confirmatory assay
for anti-HBc. This is unfortunate since even the most
recent generation of assays still generate substantial
false positivity. Because of insufficient confirmatory
assays, re-testing with an alternative assay is a good
HBsAg substitute provided sensitivity is equivalent. Sensitivity
Total anti-HBc can be assessed against the standard set by WHO.
IgM anti-HBc
Anti-HBs The titre of anti-HBc could also be useful in defining
Detectable level the significance of a result. Non-specific results are often
weakly positive, occasionally are borderline positive after
repetition, and often cannot be reproduced by another
0 3 6 9 12 120 test kit. The Japanese Red Cross blood centres have
Incubation Acute phase Serum Resolved phase reported that blood donors with low anti-HBc titre
phase conversion (signal-to-cutoff ratio values between 1·0 and 11·9) could
carry low amounts of HBV DNA, suggesting occult
B
HBV infection and such donations were infectious to
HBV DNA
recipients. As a result, all anti-HBc reactive donors are
rejected.26,27 A higher anti-HBc titre (signal-to-cutoff
HBeAg Anti-HBe ratio ≥12·0) is more likely to imply past (or present)
infection. However, overall, it is unclear what fraction of
the total anti-HBc alone results reported in patients are
false-positive, and how many provide true evidence for
past hepatitis B exposure. Table 1 shows a summary of
the relevant studies with respect to this point.20,28–35

Co-infection with HIV or HCV

Detectable level
Several studies7,36–40 have reported an association between
the presence of anti-HBc alone and HCV or HIV
co-infection. Thus, viral interference by other viruses in
0 3 6 9 12 120 the replication or immune response to HBV could be
Incubation Acute phase Serum Chronic phase involved in the occurrence of anti-HBc alone. Putative
phase conversion mechanisms such as downregulation of HBV gene
Months after HBV exposure expression and mutations in the HBV genome could
Figure 1: Serum HBV DNA, antigen, and antibody responses during HBV exposure in acute, resolved (A), modulate the cellular and humoral immune response
and chronic (B) forms to HBV.
Many published reports support the observation that
samples that were positive for anti-HBc by enzyme the serological anti-HBc only positivity is a common
immunoassay and negative by radioimmunoassay, also clinical finding in patients with hepatocellular carcinoma
had low concentrations of anti-HBc. In a study20 in infected with HCV,41–44 suggesting potential interference
which 133 individuals who were anti-HBc alone-positive between HBV and HCV replication. Inigo and colleagues45
were tested by enzyme immunoassay, re-testing by revealed that HCV core protein suppresses HBV
radioimmunoassays revealed that 26% of samples replication and HBsAg production, thus affecting its
became anti-HBc negative. Additionally, circulating HBV detection in the bloodstream of patients co-infected with
DNA was undetectable in 96% of these anti-HBc alone HCV and HBV. HCV could suppress not only the
positive (by enzyme immunoassay) serum samples. replication of HBV but also the expression of HBV
Cross-reactivity with interfering serum substances or envelope proteins in vitro and in vivo.46,47 Furthermore,
with immune globulin IgA—or IgM—molecules several studies have found that HIV-infected individuals
secreted by non-specific HBV-activated B lymphocytes might frequently be co-infected with HBV, and anti-HBc
could be another cause of anti-HBc false-positivity.21–23 is usually the only positive HBV serological marker
Pretreatment of blood samples with reducing agents indicating persistent HBV infection in this group.9,10
(eg, dithiothreitol [25oC; +DTT] or potassium bisulfite Most recently, a study from Switzerland,1 where the
[37oC; +MBS]) can help avoid non-specific false prevalence of HBV infection is low, found that 23 of
anti-HBc positivity.24,25 Thus, differences in pretreatment, 31 (74·2%) patients with anti-HBc alone status were

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Chronic infection Resolved infection Passive transfer

• Latent chronic carriers • HBsAg–anti-HBs immune complexes • ie, blood transfusion, infant born to HBsAg(+)
• Genetic variants of HBV cause serum mutant • Window phase (HBsAg has disappeared and mother, after intravenous immunoglobulin
HBsAg and thus no anti-HBs detection anti-HBs not yet appeared) therapy
• Loss of anti-HBs after decades

Anti-HBc negative False positive reactivity

(especially, people from regions of
low HBV endemicity)
Confirmed by
• Second assay (ie, radioimmunoassay of
anti-HBc
• Second test

Acute infection
Anti-HBc positive • IgM anti-HBc(+)
• 1–3 months later anti-HBs(+)

Other HBV serological markers positive:

• HBeAg, anti-HBe Chronic infection
• HBV DNA
Defining features of anti-HBc
alone serological status
• Anti-HBc(+)
• HBsAg(–) Most occur in
• Anti-HBs(–)

Co-infection
• ie, HCV, HIV Resolved infection

Passive transfer
Primary response

Hepatitis B vaccine No response

Anamnestic response

Figure 2: Flow chart: Algorithmic approach for anti-HBc alone constellation under different clinical courses
HBV=Hepatitis B virus. HBsAg=Hepatitis B surface antigen. HBeAg=Hepatitis B envelope antigen. HCV=Hepatitis C virus.

co-infected with HCV. In this cohort, infrequent window of a recent infection.49–55 However, excluding
intrahepatic total HBV DNA (two of 22 patients, 9·1%) recent HBV infection, HBsAg in small amounts can still
and complementary closed circular DNA (one of 22, be present in patients persistently infected with HBV
4·5%) tested by nested PCR were detected in liver that are beyond the detection capability of available
biopsies. Our group used recombinant proteins HBsAg assays. Moreover, presence of HBsAg can be masked
(ay subtype) and HBsAg (ad subtype), an HBV core by non-neutralising circulating anti-HBs molecules.56
(1–186 aminoacids), and a total number of 49 HBsAg— Presence of HBV infection in such patients can be
and HBcAg—derived peptides for analyses; all patients verified through detection of HBV DNA by PCR.13,56
who were positive for anti-HBc positive showed an The finding of anti-HBc without HBsAg in patients
HBV-specific T-cell and memory B-cell response typical with chronic hepatitis with still undetermined cause is
for past viral exposure and protective immune memory, difficult to interpret, since the absence of HBsAg does
suggesting resolved HBV infection.48 Consequently, in not invariably exclude a causative role for HBV. Detection
view of the high frequency of HCV and HIV co-infection of high titres of anti-HBc could support this assumption.
in patients with anti-HBc alone status, HCV and HIV Testing for anti-HBe is sometimes advised in such cases.
antibodies should also be tested in these patients. Moreover, spontaneous or iatrogenic generation of
HBsAg mutants could lead to evasion of immune
Failure to detect HBsAg in patients positive for detection of circulating HBsAg by conventional immuno-
anti-HBc assays. HBV has a higher frequency of mutations than
HBsAg could remain negative in blood for up to other DNA viruses because the virus replicates via an
6 months after exposure and infection with HBV—ie, in RNA intermediate, by use of a reverse transcriptase that
blood donors who are within the so-called immunological does not have a proof-reading function. This mechanism

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 Review

depend on mutations in the “a” determinant, although

nucleotide deletion in the core promoter region might
Blood
HBsAg also cause lower amounts of S gene expression or viral
CD8 replication.65–73 A frame shift in the open reading frames
HBeAg
(ORFs) of the S gene on one of three clones suggested that
there was a counter-selection against production of
Core
Immuno-responses HBsAg.74 Such mutations could lead to aberrant HBsAg
HBcAg
Efficient Low molecules that cannot be detected with licensed screening
CD4
HBV
memory antigen tests, but can be verified by use of unconventional enzyme
T cells doses
immunoassays with monoclonal antibodies.
HBeAg The hepatitis B virus has overlapping ORFs. A potential
effect of nucleoside analogue therapy on HBV mutations,
and concomitant HBV S gene mutations has been
HBV infection
Spherical and shown.75,76 This effect has been noted in individuals
filamentous HBsAg
co-infected with HBV and HIV and treated with anti-HIV
SVP
therapy such as lamivudine.77
It has been clearly indicated that aminoacid
substitutions in the major hydrophilic region affect
Virions Hepatocyte HBsAg detection, in particular, substitution of cysteine
residues.78,79 Different tests are able to detect different
MVB Golgi specific mutations, some are not detected at all.80 Of the
Cytoplasm many described mutations for HBsAg, the most common
described mutations are G145R, P120S, P120T, A128V,
and T118A.81,82 Such mutations could lead to aberrant
Uncoating HBsAg molecules that cannot be detected. As a result,
Recycling
testing anti-HBc only samples with several HBsAg assays
might reveal such false negative cases. Biswas and
HBcAg HCV
Endoplasmic colleagues83 reports that major hydrophilic region
HIV
reticulum mutations, mutations in the core gene, frame shifts and
also immune complexes masking HBsAg (and anti-HBs)
Co-infection Core particle
interferences minus and plus
and major hydrophilic region mutations are associated
HCV
HIV
strand synthesis with a reduction in HBsAg excretion.
Core assembly and
Genetic
variants
RNA packaging Different phases during HBV infection
RC DNA Acute window phase
HBcAg
The average incubation period of acute hepatitis B is
HBeAg 90 days (range 60–150).84,85 Total (IgG and IgM) anti-HBc
HBV and IgM anti-HBc appear at the onset of clinical symptoms
DNA
HBV RNA and rapidly reach peak concentrations. An IgM class of
HBsAg
HCV anti-HBc is often considered to be a precise marker for the
differential diagnosis between acute hepatitis B (persists
Nucleus HBcAg
Protein for up to 6 months if the disease resolves) and acute
variants exacerbation-reactivation of chronic HBV infection.1
However, anti-HBc can also be detected at high titres by
qualitative assays in exacerbation of chronic hepatitis B.86
Figure 3: Possibilities and clinical courses of anti-HBc alone
The difficulty in obtaining high amounts of IgM anti-HBc
RC DNA=relaxed circular DNA. SVP=subviral particles. MVB=multivesicular bodies.
with such a test should be mentioned, particularly
could lead to generation of point mutations, deletions, regarding specificity. The decrease in IgM anti-HBc titres
and re-arrangements in the HBV genome, which lead during convalescence occurs at variable rates, although
to modulations of HBsAg expression, secretion, and IgG anti-HBc generally persists for life. The highest titres
synthesis despite active viral replication. Mutations in the occur in patients with persistent infection.87–90 Once the
major hydrophilic region (MHR) of the S protein could anti-HBc alone profile is confirmed by repeated anti-HBc
affect the binding of the mutated surface antigen to testing, anti-HBs should be tested after another
anti-HBs antibodies detected through routine enzyme 1–3 months. Anti-HBs seroconversion will support that
immunoassays. Thus, such HBsAg mutants escape the initial anti-HBc positivity had been recorded during
detection, leading to a serological profile of anti-HBc the so-called acute window period, especially when IgM
alone.57–64 For example, insufficient HBsAg detection could anti-HBc is positive (figure 1).

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Patients confirmed as False positive anti-HBc alone serological status (%) Past HBV exposure of patients with ant-HBc alone
having anti-HBc alone serological status (%)
serological status (%)
Lok et al28 214/1801 patients (11·9%) 120/214 patients with primary response (56%) 16% (anamnestic or secondary anti-HBs response)
Chan et al29 ·· 37/88 patients (42%) 37/49 patients were positive for anti-HBe or HBV DNA
(75·5%)
Su et al30 21/1734 patients (1·2%) 8/21 patients (38%) 13/21 patients with anamnestic response, none had
evidence of HBV DNA (61·9%)
Lu et al31 18/1454 patients (1·2%) 1/18 patients (5·6%) 14/18, 12 patients with anti-HBc alone responses
developed an anamnestic, anti-HBs response, two were
positive for HBV DNA (77·8%)
Ural et al32 ·· 23/48 patients with primary response (47·9%) 20/48 patients with anamnestic response (41·6%)
McIntyre et al33 ·· 7/17 patients (41·2%) 6/17 patients with anamnestic response (35·3%)
Silva et al20 ·· 66/82 patients with primary response (80·5%) 25/130 with anamnestic response (19·2%); 5/133 patients
were HBV DNA positive (3·8%)
Lai et al34 51/638 patients (8·0%) 35/48 patients with primary response (72·9%) 2/48 patients with anamnestic response (4·2%)
Sünbül et al35 ·· 9/33 patients with primary response (27·3%) 16/33 patients with anamnestic response (48·4%)

Table 1: Summary of anti-HBc alone studies with false-positive versus true-positive results

Patients with chronic hepatitis B positive and even vaccinated individuals.30,45,100–103 In many
Presence of HBsAg in serum for at least 6 months is studies,26,27 anti-HBc alone represents approximately
considered evidence for persistent HBV infection. In 40% of occult HBV infections. Therefore, any anti-HBc
people who become chronically infected, HBsAg and alone sample should be tested with highly sensitive
anti-HBc persist, typically for decades and possibly for life, HBV DNA assay—the median load is 20–25 IU/mL.
with a HBsAg clearance and anti-HBs seroconversion rate Immunisation with one dosage of an HBV vaccine could
ranging between 3% and 6%.70,91,92 Furthermore, HBV also enable a distinction between latent and occult
DNA might still be detectable in serum of asymptomatic infection groups.99 An anamnestic anti-HBs response to
HBsAg carriers and in individuals with healthy liver one HBV vaccine dosage will support the presence of an
function who test negative for HBsAg or positive for either immune memory to HBV with resolved HBV infection
anti-HBs or anti-HBc. The anti-HBc positive group could although absence of such a response or detection of
remain latent chronic HBV carriers with low frequency of HBV DNA in serum will suggest the diagnosis of occult
HBV replication, which can reactivate during periods of HBV. In patients with persistence of HBV DNA
immune suppression.93–95 synthesis, this diagnosis could be associated with liver
The interpretation of the importance of anti-HBc alone injury and progression to cirrhosis and hepatocellular
in a particular patient is directly related to the endemicity carcinoma.1 One analysis of occult HBV infection
and risk of HBV in the population tested. In patients isolated from patients with hepatocellular carcinoma
residing in regions where the population has a low HBV showed that multiple viral variants accumulated in the
prevalence, such as in most parts of Europe and the USA, liver of these patients, suggesting that the host, rather
anti-HBc alone frequently represents a false-positive than viral factors, contributed to the cryptic HBV
reaction. In such a population, a primary conventional infection.70 Kwak and others reported that 84·6% of
anti-HBs response to immunisation after a one-to-three patients with cryptogenic hepatocellular carcinoma had
dose series of hepatitis B vaccine can support the anti-HBc IgG antibodies in South Korea, but this
diagnosis of a false positive anti-HBc reaction. In subgroup had different clinical features to those of HBV
contrast, in highly endemic countries (ie, southeast Asia, patients with hepatocellular carcinoma, suggesting that
most of the Middle East, the Amazon Basin, most Pacific the presence of anti-HBc might modify the characteristics
Island groups, and sub-Saharan Africa) HBV is mainly of this carcinoma towards those of HBV hepatocellular
acquired during the perinatal or early childhood period. carcinoma.92
Therefore, anti-HBc alone is likely to indicate previous
infection, with loss of anti-HBs.1,5,96–99 Resolved phase
Not all unusual patterns of serological reaction to HBV
Occult HBV infection are due to genetic viral variants. HBsAg might be
Occult HBV infection is defined as low plasma undetectable in serum because of masking by circulating
concentrations of HBV DNA with undetectable HBsAg anti-HBs. By convention, disappearance of HBsAg
outside the pre-seroconversion window period.1 Many and seroconversion to anti-HBs antibodies after acute
studies on occult HBV infection have focused on infection indicates the resolution of HBV infection.
anti-HBc alone although many subsequent studies have During the initial period after acute infection, anti-HBc
found that occult infection can occur in anti-HBs could be present during the so-called window phase

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when HBsAg has disappeared and anti-HBs has not yet regimen (at 0, 1, and 6 months).113 Most vaccinated healthy
appeared, usually within 3–4 months.104 During this early children and adults will develop much higher anti-HBs
phase of infection, anti-HBs antibodies can also bind to concentrations than 10 mIU/mL, ranging between
their corresponding antigens, forming HBsAg-anti-HBs hundreds to thousands mIU/mL after three doses of
immune complexes.105–107 Finally, this condition could HBV vaccine.98 Non-response to vaccination is defined as
also be due to the decay and loss of immune memory anti-HBs less than 10 mIU/mL after the third dose of
decades after primary HBV infection and especially in vaccination.114 An anamnestic response was defined as a
countries where repeated exposure to HBV infected switch of anti-HBs from less than 10 mIU/mL to more
individuals with high viral load will lead to breakthrough than 10 mIU/mL 2–3 weeks after administration of
of the immune memory. Despite undetectable serum one booster vaccine dose.20,115,116 Those patients with an
anti-HBs, the HBsAg-specific T-cell-immune response anamnestic response for which the serum anti-HBs
plays an important role in protecting HBV infection and concentration was more than 10 mIU/mL but less than
replication.108 Because of this cellular immune memory 100 mIU/mL were deemed to have shown a borderline
and mechanism, anti-HBc alone individuals seem to protective status, and greater than 100 mIU/mL was
have a signature of late immunity and be protected suggested a protective anti-HBs status.117
against re-infection. HBV-resolved individuals with In patients who develop a primary response to three
undetectable concentrations of anti-HBs antibodies will doses of the vaccine, an anti-HBc alone positivity is
develop a strong secondary immune response after the presumably false-positive.35 No response to vaccination
hepatitis B vaccine.109 suggests occult HBV infection—which should be
It is noteworthy that anti-HBc can also indicate confirmed by HBV DNA testing—although an
resolution of long term chronic infection (ie, not just anamnestic response is consistent with past infection
resolution of acute infection). About 1–2% of chronic and immunity.20 It should be noted that occult HBV
hepatitis B carriers (especially long-term inactive carriers) infection with anti-HBc alone can occur in vaccinated
can spontaneously lose HBsAg with or without presence individuals with low anti-HBs or no detectable anti-HBs.
of anti-HBs antibodies.1,110 This response is associated with contact with high viral
load HBV of a genotype other than A1 (the vaccine’s
Passive transfer of antibodies genotype) as reported by Stramer and colleagues.118
Anti-HBc can be passively acquired through transfusion Several studies20,48,101,116 have assessed the anti-HBs
with anti-HBc-positive blood. Infants who do not become response to immunisation with an HBV vaccine in
infected born to mothers positive for HBsAg could have patients with anti-HBc alone status. A rapid and robust
detectable anti-HBc for up to 24 months post partum as response to a booster vaccine suggests a long-lasting
a result of passively transferred maternal anti-HBc anamnestic response.119 Similarly, in a study101 from
antibodies. Furthermore, intravenous immunoglobulin—a Taiwan, among 46 children who were vaccinated against
plasma-derived product consisting of concentrated HBV at birth, two children (4·3%) were anti-HBc alone
immunoglobulin—could contain anti-HBc antibodies at an age of 6–8·9 years old. One study119 in health-care
that might be passively transferred to recipients. A workers who were vaccinated against HBV as adults,
retrospective study found an odds ratio of 16 (95% CI reported that anti-HBs concentrations decreased
1·5–166·1) for anti-HBc positive participants who had 10–31 years after vaccination and fell lower an amount
previous intravenous immunoglobulin infusions.111 The considered protective in 25% of cases.119 From our group’s
antibodies passively acquired through administration of data,48 2–3 weeks after the administration of one dose of
intravenous immunoglobulin have an estimated 21–24 day HBV vaccination, in two (33·3%) of six patients with
half-life and are usually cleared from the circulation.112 anti-HBc alone status, anti-HBs antibody concentrations
Thus, patients with anti-HBc alone should be interviewed in plasma became greater than the protective cutoff, with
regarding treatment with intravenous immunoglobulin or one patient having a titre of 10 mUI/mL and the other
blood product transfusion and retested for anti-HBc 12 mUI/mL. However, this increase in anti-HBs was
within 3–6 months of presumed exposure.83 accompanied by an expansion of HBsAg-specific
memory B cells, which were significantly stronger in the
The role of HBV vaccination in clarifying the significance B cell enzyme-linked immunospot assay than before
of isolated anti-HBc antibodies vaccine (p=0·0226).48 These data showed that immune
Hepatitis B vaccines are formulated to contain 3–40 μg of memory against HBV infection lasts longer than
HBsAg protein per mL and an aluminium phosphate or anti-HBs antibodies. Table 2 describes an anamnestic
aluminium hydroxide adjuvant. The pattern of anti-HBs response in anti-HBc alone individuals and in patients
response to hepatitis B vaccine could provide additional immunised to HBV about 20 years ago.30,48,109,117,120,121
diagnostic information for interpreting an anti-HBc Of note, anti-HBs tends to become undetectable
alone result. Primary response and seroprotection against relatively early, so anti-HBc alone is typically a recovered
HBV is defined as more than 10 mIU/mL of anti-HBs infection with undetectable anti-HBs. Also, HBsAg tends
one month after a standard three-dose vaccination to decline over a much longer period of time but can

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Patient population (%) Low (<10 mIU/mL) Medium (10 to 100 mIU/mL) High (≥100 mIU/mL)
Su et al117
Anti-HBc alone 1·7 (14/843 patients) ·· ·· ··
HBV naive* 62·3 (525/843 patients) 24·7% (78 of 316 patients) 23·4% (74 of 316 patients) 51·9% (164 of 316 patients)
Hudu et al120
Anti-HBc alone 5·0 (20/408 patients) 0 100% 0
Su et al30
Anti-HBc alone 0·7 (13/1734 patients) 7·7% (1 of 13 patients) 61·5% (8 of 13 patients) 30·8% (4 of 13 patients)
HBV naive*† 58·2 (1010/1734 patients) ·· ·· ··
Wang et al67
Anti-HBc alone 31 patients 66·7% (4/6) 33·3% (2/6) 0 (0/6)
Gessoni et al109
Anti-HBc alone 0·8 (31/3992 patients) 66·7% (14/21) 28·6% (6/21) 4·8% (1/21)
Bagheri-Jamebozorgi et al121
HBV naive*‡ 63·0 (189/300 patients) ·· ·· ··

*HBV naive: individuals with full HBV vaccination in infancy and with the status of HBsAg negativity, anti-HBc negativity and anti-HBs negativity in adulthood. †There was
no significant difference in anamnestic response to the vaccine booster dose between the geometric mean titre of anti-HBs antibodies in patients with true anti-HBc alone
(50·6 mIU/mL) and HBV naive (47·7 mIU/mL) serological status. ‡138 patients who were HBV naive received a booster dose, of whom 125 (90·6%) of 138 had an anamnestic
response. The columns with Low, Medium, and High represent the anti-HBs titre.

Table 2: Anamnestic responses in studies of individuals who have anti-HBc alone or HBV naive serological status after booster vaccination

become undetectable, leaving anti-HBc as the only lymphoma or undergoing haematopoietic stem cell
marker of chronic infection, although HBsAg-specific transplantation. Patients who are anti-HBc alone and
T cell immune responses can still play an important role patients with anti-HBc-positive and anti-HBs-positive
in protecting against HBV infection and replication.122,123 serological status are also at risk for HBV reactivation
In both situations, sensitive detection of HBV DNA is under conditions of immune suppression although this
crucial to diagnosis. risk is lower compared with patients with HBsAg-positive
and anti-HBc-positive serological status.
The significance and clinical implications of Organ donor shortage has led to an expanded use of
anti-HBc alone in organ donors and patients grafts from donors who are anti-HBc-positive only or
receiving chemotherapy or immunosuppressive donors with anti-HBc-positive and anti-HBs-positive
therapy serological status with past exposure to hepatitis B,
HBV reactivation is a serious, often life-threatening especially in areas in which the prevalence of HBV is
complication that affects many risk groups including high.128–130 If possible, anti-HBc-positive grafts should first
patients given chemotherapy and immunosuppressive be transplanted into recipients who have HBV-related
therapy and organ transplant recipients. There is a liver disease, second to those with antibodies to HBV,
worldwide consensus that patients positive for HBsAg and last to patients with no history of HBV. Recipients
should be protected against HBV reactivation when who are anti-HBc-positive are not absolutely protected
receiving immunosuppressive therapy.1 Reactivation and should be given prophylaxis. The mandatory use of
can occur in patients who are HBsAg-positive or immunosuppression in organ transplant recipients
HBsAg-negative if they are also positive for anti-HBc.124 favours reactivation of a latent virus. Most acquired HBV
Unfortunately, antiviral prophylaxis was infrequently infections after liver transplantation are in relation to the
administered to patients with cancer receiving donated liver.130,131 Organ donors who are anti-HBc-positive
chemotherapy. A survey done by the members of the have been implicated as a potential source of HBV
American Association for the Study of Liver Diseases transmission in 25–95% of the recipients of orthotopic
reported that the overall frequency of prechemotherapy liver transplants; whereas, the risk of de-novo infection
HBV screening was only 188 (53%) in a cohort of in recipients who are anti-HBc alone positive who have
355 patients with cancer. Moreover, 23% of the patients not received prophylactic therapy after these transplants
who had reactivated HBV died of liver failure.125 However, range from 0% to 18%.131–140 Additionally, HBV reactivation
there still is a debate regarding the means for protection can also occur in other solid-organ transplants including
of patients positive for anti-HBc who have cancer renal, heart, and lung transplants.130
chemotherapy or patients who receive organ transplants Another risk group for HBV reactivation includes
from donors of anti-HBc alone status. Some studies126,127 anti-HBc-positive alone patients with blood cancer and
have found a benefit of antiviral prophylaxis in patients patients with rheumatic diseases. One study141 from 2014
who are HBsAg-negative and anti-HBc-positive with highlighted the reactivating risk in anti-HBc-positive

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 Review

Approach Goals of treatment

High risk: HBsAg-positive Treated with oral antiviral agents (eg, entecavir/tenofovir) 1–2 weeks before Normalisation of alanine aminotransferase,
patients, including both and no later than on the first day of immunosuppression therapy. Antiviral suppression of HBV viral load to undetectable
detectable and undetectable therapy should continue for at least 6–12 months after completion of levels, and HBeAg seroconversion to anti-HBe.
HBV DNA chemotherapy or immunotherapy. Prolonged antiviral treatment for an In anti-HBe-positive patients, alanine
undefined period and possibly lifelong should be considered in patients with aminotransferase normalisation and viral-load
advanced liver disease or with baseline high viral load. suppression are the main goals of treatment
Low risk: Occult HBV infection Not universally accepted. In case of HBV reactivation, as assessed by Prevention of HBV reactivation
(HBsAg-negative/anti-HBc- significant increase in HBV DNA levels, they should be promptly treated
positive with or without anti-HBs with antiviral drugs, possibly before alanine aminotransferase increases.
and undetectable HBV DNA) Oral antiviral agents (eg, lamivudine).

Table 3: Clinical approach in the risk of HBV reactivation

carriers who were patients with non-Hodgkin and virological breakthrough is substantially lower in
lymphoma, chronic lymphocytic leukaemia, or individuals with low concentrations of HBV DNA.
rheumatoid arthritis given rituximab-based therapy. Lee However, it should be noted that resistance to lamivudine
and colleagues100 reported that HBV reactivation was emerges at high rates (30–50% cases within a year), in
found in 1·7% (eight of 468) patients who were contrast to tenofovir (0%).1,110 hepatitis B immunoglobulin
HBsAg-negative or anti-HBc-positive with rheumatic alone does not seem to be absolutely effective in
diseases when treated with anti-tumour necrosis factor.100 preventing transmission of HBV, although nucleoside
No definite HBV reactivations were found in patients analogues either alone or in combination with hepatitis
who were anti-HBc-positive and insufficient HBsAg in B immunoglobulin are effective.1,98,138,156–161 Although
an inflammatory bowel disease cohort treated with anti-HBs and nucleoside analogues have different
immunosuppressants.142 mechanisms to provide protection that could complement
Reactivation of HBV could be triggered by each other, a systematic review has shown that published
chemotherapy, biological therapies (particularly studies have not found the combination of hepatitis B
rituximab), or a modification in patient’s immune immunoglobulin and lamivudine therapy to be more
function.143–152 At present, the most reliable test in clinical effective than lamivudine treatment alone; furthermore,
practice to diagnose HBV reactivation is the rise of one the single treatment is more practical and affordable.
log in serum HBV DNA concentrations. When HBV Nucleoside analogue monotherapy should therefore be
reactivation is diagnosed, it is suggested to start antiviral considered in preventing HBV infection in transplant
treatment immediately (table 3).153,154 It is still debated recipients who are HBsAg and HBV DNA negative
whether it is mandatory to treat all cases that have a one when given donor tissue from individuals who are
log HBV DNA increase without a rise in alanine anti-HBc positive.162 Since hepatitis B immunoglobulin
aminotransferase and without HBsAg reappearance. administration is an expensive and inconvenient
Thus, it could be argued that cases with small increases preventive measure to acquire anti-HBs after liver
in HBV DNA concentrations (ie, from undetectable to transplantation, active immunisation for recipients, such
one or two log using a sensitive PCR assay) could still be as pre-transplant HBV vaccination, can be used.
acceptable to continue monitoring. Successful active immunisation before transplantation
In patients who are HBsAg-negative or and lamivudine after the procedure might be sufficient to
anti-HBc-positive and who are receiving systemic prevent de-novo hepatitis B.163 One literature review164
chemotherapies or biological therapies that modify their including 39 studies with 903 recipients of anti-HBc
immune function, the risk of hepatitis B reactivation is positive liver grafts, showed both anti-HBc and anti-HBs
1–2·7%.155 Effective prophylaxis against HBV reactivation positive recipients might need no prophylaxis at all.
should be used in these situations. Related strategies for
prophylaxis should be implemented in such recipients to Conclusion
reduce or eliminate the risk of developing post-transplant In summary, anti-HBc is present during different phases
de-novo hepatitis B infection from anti-HBc positive of hepatitis B virus infection. Anti-HBc alone serological
donors.156 These include passive immunoprophylaxis status is compatible with acute, resolved, and overt or
with hepatitis B immunoglobulin and drug prophylaxis occult chronic HBV infection. The pattern of anti-HBs
with nucleoside analogues (ie, lamivudine, tenofovir, and response to hepatitis B vaccine and HBV DNA testing
entecavir), separately or in combination. Prophylaxis could provide additional diagnostic information for
against reactivation might not require more potent and interpreting an anti-HBc alone result. Anti-HBc-positive
costly nucleoside analogues (ie, entecavir and tenofovir). organ donors are a potential source of hepatitis B virus
Lamivudine might be more cost-effective, especially in transmission to their recipients. Reactivation of occult
anti-HBc-positive and HBsAg-negative individuals with HBV can be triggered by chemotherapy, biological
low-level viraemia. The risk of antiviral resistance therapies (particularly rituximab), or modulation of

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 Review

11 Wedemeyer H, Cornberg M, Tegtmeyer B, Frank H, Tillmann HL,

Search strategy and selection criteria Manns MP. Isolated anti-HBV core phenotype in anti-HCV-positive
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Contributors 19 Parkinson AJ, McMahon BJ, Hall D, Ritter D, Fitzgerald MA.
QW did the literature research. All authors contributed to the writing and Comparison of enzyme immunoassay with radioimmunoassay for
editing of the manuscript. NS and QW created the figures and tables. the detection of antibody to hepatitis B core antigen as the only
Declaration of interests marker of hepatitis B infection in a population with a high
prevalence of hepatitis B. J Med Virol 1990; 30: 253–57.
We declare no competing interests.
20 Silva AE, McMahon BJ, Parkinson AJ, Sjogren MH, Hoofnagle JH,
Acknowledgments Di Bisceglie AM. Hepatitis B virus DNA in persons with isolated
We thank Daniel Shouval (Liver Unit, Hadassah-Hebrew University antibody to hepatitis B core antigen who subsequently received
Hospital, Jerusalem, Israel) for helpful comments and discussion of the hepatitis B vaccine. Clin Infect Dis 1998; 26: 895–97.
manuscript. QW was supported by a grant from the National Natural 21 Weber B, Melchior W, Gehrke R, Doerr HW, Berger A, Rabenau H.
Science Foundation of China (81570511). PK was funded by the Hepatitis B virus markers in anti-HBc only positive individuals.
Wellcome Trust (WT 091663MA), the NIHR Biomedical Research J Med Virol 2001; 64: 312–19.
Centre Oxford, and the Oxford Martin School. NS received funding 22 Sallberg M, Magnius LO. Enzyme immunoassay for anti-hepatitis B
from the Gertrud and Walther Siegenthaler Foundation, Zurich, core (HBc) immunoglobulin G1 and significance of low-level results
Switzerland. in competitive assays for anti-HBc. J Clin Microbiol 1989; 27: 849–53.
23 Robertson EF, Weare JA, Randell R, Holland PV, Madsen G,
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