The biological meaning of anti-HBC positive result in blood donors: relation to HBV-DNA and to other serological markers

Safety of Hepatitis B Virus Screening in Blood Donors from the Hospital Foundation of Hematology and Hemotherapy of the State of Amazonas (HEMOAM) in the Brazilian Amazon

BACKGROUND

Hepatitis B is an infectious disease of worldwide importance and of great interest to transfusion medicine. The Amazon region has areas of high endemicity, outlining a worrying scenario for transfusion and epidemiological safety.

OBJECTIVE

To analyze the profiles of serological and molecular markers for HBV of blood donors from HEMOAM.

METHODS

Blood donors with different patterns of reactivity in serological and molecular screening for HBV were tested for viral load by the qPCR method at the reference center for liver diseases in the state of Amazonas.

RESULTS

A total of 230,591 donors were tested, with 3104 (1.34%) found reactive for HBV and 2790 (89.9%) found reactive for isolated anti-HBc. Viral load was not detected in 100% of donors reactive only to HBsAg, while 100% of donors with positive anti-HBc and positive HBsAg or HBV NAT demonstrated a detectable viral load. We also detected one case of occult hepatitis B (0.03%) only with reactive HBV NAT and five donors (0.2%) with positive anti-HBc and HBV NAT.

CONCLUSIONS

With this result, the great importance of the anti-HBc test for the unsuitability of blood donors was verified, as well as the fundamental introduction of the HBV NAT test in screening for hepatitis B in Brazilian blood banks, as this was the only way to detect the viral infection burden in asymptomatic donors who previously would not be treated, which contributed to the maintenance of the endemicity of hepatitis B in the Brazilian Amazon.

Are current screening protocols for chronic hepatitis B virus infection adequate?

Chronic hepatitis B virus (HBV) infection screening usually includes only HBV surface antigen (HBsAg) testing; HBV core and surface antibody (anti-HBc, anti-HBs) assays, indicating resolved infection and immunity, are not routinely performed. Yet, serum HBV DNA is measurable in approximately 10% of HBsAg-negative/anti-HBc-positive cases, representing occult HBV infection (OBI). Patient blood samples from 2 Veterans Affairs medical center look-back investigations were screened for HBV infection using HBsAg enzyme immunoassays. Supplementary testing included anti-HBc and anti-HBs enzyme immunoassays. For anti-HBc-positive samples, HBV DNA testing was performed. Background OBI prevalence was further estimated at these 2 facilities based on HBV serology testing results from 1999-2012. Finally, a literature review was performed to determine OBI prevalence in the published literature. Of 1887 HBsAg-negative cohort patients, 98 (5.2%) were anti-HBc positive/anti-HBs negative; and 175 (9.3%), anti-HBc positive/anti-HBs positive. Six of 273 were HBV DNA positive, representing 0.3% of the total tested and 2.2% who were anti-HBc positive/anti-HBs negative or anti-HBc positive/anti-HBs positive. Among 32,229 general population veterans at these 2 sites who had any HBV testing, 4/108 (3.7%) were HBV DNA positive, none of whom were part of the cohort. In 129 publications with HBsAg-negative patients, 1817/1,209,426 (0.15%) had OBI. However, excluding blood bank studies with greater than 1000 patients, the OBI rate increased to 1800/17,893 (10%). OBI is not rare and has implications for transmission and disease detection. HBsAg testing alone is insufficient for detecting all chronic HBV infections. These findings may impact blood donation, patient HBV screening, follow-up protocols for patients assumed to have cleared the infection, and initiation of immunosuppression in patients with distant or undetected HBV.

Occult hepatitis B virus infection among blood donors in Colombia

Background

Hepatitis B virus (HBV) surface antigen (HBsAg) screening in blood banks reduced the risk of HBV transmission through transfusion. However, the detection of occult HBV infection among blood donors is imperative for improving blood safety. The aim of this study was to determine the frequency of occult hepatitis B virus infection among blood donors in Medellin, North West Colombia and to characterize the viral genotypes and mutations.

Methods

Serum samples from blood donors with the serological profile HBsAg-/Anti-HBc+ were evaluated by nested or hemi-nested PCR for HBV genome ORF C, ORF S and ORF X. A pairwise analysis was carried out with deduced amino acids sequence of overlapping S/P region.

Results

A total of 302 serum samples HBsAg-/Anti-HBc+ from donors recruited in a blood bank in Medellin were evaluated by PCR for the HBV genome. Six samples (1.98%) were identified as occult HBV infection. The cases were confirmed by sequencing and viral load analysis. All HBV strains were genotype F, subgenotype F3. The amino acid substitutions sY100H, sV184A, and sK141N were detected in ORF S and rtL108P, rtR110G, rtL180M, rtR192C, rtT150S, and rtL187V in ORF P.

Conclusions

This is the first report and characterization of OBI cases in blood donors in Colombia. Six from 302 donors HBsAg-/Anti-HBc+ were identified. The mutations rtL108P, rtR110G, rtR192C, rtT150S and rtI187V were characterized for the first time in these samples. Further studies are necessary to explore if these mutations could potentially impair HBsAg production.

Occult hepatitis B virus infection among blood donors from the Brazilian Amazon: implications for transfusion policy

BACKGROUND

Brazil requires the performance of both a test for hepatitis B surface antigen (HBsAg) and a test for antibodies to the core of hepatitis B for blood donor screening. Blood centres in regions of high HBV endemicity struggle to maintain adequate stocks in face of the high discard rates due to anti-HBc reactivity. We evaluated the potential infectivity of donations positive for anti-HBc in search of a rational approach for the handling of these collections.

STUDY DESIGN AND METHODS

We tested anti-HBc reactive blood donations from the state of Amazonas for the presence of HBV DNA and for titres of anti-HBs. The study population consists of village-based donors from the interior of Amazonas state.

RESULTS

Among 3600 donations, 799 were anti-HBc reactive (22·2%). We were able to perform real-time PCR for the HBV S gene on specimens from 291 of these donors. Eight of these samples were negative for HBsAg and positive for HBV DNA and were defined as occult B virus infections (2·7%). Six of those eight specimens had anti-HBs titres above 100 mIU/ml, indicating the concomitant presence of the virus with high antibody titres.

CONCLUSION

A small proportion of anti-HBc reactive donors carry HBV DNA and anti-HBs testing is not useful for predicting viremia on them. This finding indicates the possibility of HBV transmission from asymptomatic donors, especially in areas of high HBV prevalence. Sensitive HBV DNA nucleic acid testing may provide another level of safety, allowing eventual use of anti-HBc reactive units in critical situations.

Hepatitis B virus management to prevent reactivation after chemotherapy: a review

PURPOSE

Reactivation of hepatitis B virus (HBV) infection after chemotherapy can lead to liver failure and death. Conflicting recommendations regarding HBV screening in cancer patients awaiting chemotherapy mean that some patients at risk for HBV reactivation are not being identified and treated with prophylactic antiviral therapy.

METHODS

We performed a narrative review of the existing evidence regarding screening for and management of HBV infection among patients with cancer using Ovid Medline, PubMed, and the Cochrane Library.

RESULTS

Our review showed inconsistencies in the definition and management strategies for HBV reactivation. The timeframe of reactivation is variable, and its molecular mechanisms are not clear. There are five effective antiviral agents that can be used as prophylaxis to prevent reactivation of HBV infection in cancer patients; however, the optimal drug and duration of therapy are unknown. Reactivation is more commonly reported in patients with hematologic malignancies receiving rituximab treatment, but reactivation can occur after other chemotherapies and in patients with solid tumors. Screening with all three screening tests-HBsAg, anti-HBc, and anti-HBs-allows the most thorough interpretation of a patient's serologic profile and assessment of reactivation risk; however, decision-making and cost-effectiveness studies are needed to determine optimal screening strategies.

CONCLUSIONS

Prevention of reactivation of HBV infection depends on identification of patients at risk and initiation of antiviral prophylaxis, but data to guide screening and treatment strategies are lacking. Additional research is necessary to accurately define and predict reactivation, identify best antiviral treatment strategies, and identify cost-effective HBV screening strategies.

Significance of detecting anti-HBc among Egyptian male blood donors negative for HBsAg

BACKGROUND

Screening for hepatitis B virus surface antigen (HBsAg) reduces the risk of transfusion-transmitted hepatitis B viral (HBV) infection. However, the absence of HBsAg in the blood of apparently healthy individuals may not be sufficient to ensure the lack of circulating HBV. Blood containing anti-hepatitis B core antibody (anti-HBc) without detectable presence of HBsAg might be infectious; therefore, screening for anti-HBc has been implemented in some countries resulting in a decrease in the risk of post-transfusion HBV infection.

AIM

To study the seroprevalence of anti-HBc. The relationship between anti-HBc positivity and the presence of circulating HBV among healthy blood donors negative for HBsAg will be helpful to decide whether supplemental testing may bring additional safety to blood products.

MATERIAL AND METHODS

A total of 1026 serum samples collected from HBsAg-negative Egyptian healthy male donors were tested for the presence of anti-HBc (both IgM and IgG types) using the competitive enzyme-linked immunosorbent assay technique. Anti-HBc-positive samples were subjected to real-time polymerase chain reaction to confirm the presence of HBV DNA.

RESULTS

Of the 1026 samples tested, 80 (7·8%) blood samples were found to be reactive to anti-HBc. Of those, HBV DNA was detected in five of the samples (6·25%). The levels of detected viraemia were variable among the five donors.

CONCLUSION

This study shows the insufficient effectiveness of HBsAg screening in protecting blood recipients from HBV infection. Inclusion of anti-HBc testing should be considered in the screening of blood donors.

The underlying mechanisms for the 'anti-HBc alone' serological profile

The serological pattern, "anti-HBc alone", characterized by the presence of antibodies against the core antigen of hepatitis B virus (anti-HBc) as the only marker of hepatitis B, is not rare in a diagnostic setting. Depending on the prevalence of HBV infection and the patient group investigated, 1-31% of positive anti-HBc results are isolated positive findings. Anti-HBc alone is frequently observed in intravenous drug addicts, HIV-infected individuals, patients who are coinfected with HBV and hepatitis C virus, and pregnant women. However, it is not clear how this profile should be interpreted. Several studies have shown that anti-HBc alone is not only compatible with acute and resolved HBV infection but also with chronic infection. The reasons for the lack of HBsAg and anti-HBs in anti-HBc-alone individuals are not clear, but several mechanisms and possibilities have been suggested that could explain this phenomenon, some of which are delineated in this article.

Detection of antibodies to hepatitis B core antigen using the Abbott ARCHITECT anti-HBc assay: analysis of borderline reactive sera

Routine use of the automated chemiluminescent microparticle immunoassay Abbott ARCHITECT anti-HBc for diagnosis of hepatitis B is limited in case of borderline reactive sera with low signal close to the cut-off index. In order to determine the significance of anti-HBc detection when borderline reactivity occurs using the ARCHITECT anti-HBc assay, a comparative study was designed. 3540 serum samples collected over a 2-month period in the hospital of Nice were examined for markers of HBV infection (HBsAg, anti-HBs and anti-HBc). One hundred seven samples with sufficient volume and with borderline reactivity by the ARCHITECT assay were tested by two other anti-HBc assays, a microparticle enzyme immunoassay (MEIA, AxSYM Core, Abbott Laboratories, IL, USA) and an enzyme linked fluorescent assay (ELFA, VIDAS Anti-HBc Total II, bioMérieux, Lyon, France). Only 46 samples were confirmed by the AxSYM and the VIDAS assays. Additional serological information linked to patient history showed that the remaining samples (61) were false positives (11), had low titer of anti-HBc antibodies (13), or were inconclusive (37). This comparative study highlighted the existence of a grey zone around the cut-off index. Confirmative results through a different immunoassay are needed to confirm the diagnosis of HBV on borderline reactive sera using the ARCHITECT anti-HBc assay.

Soroprevalência de infecções por vírus da hepatite B e vírus da hepatite C em indivíduos do Estado do Pará

As hepatites B e C continuam sendo um importante problema de saúde pública no Brasil. Neste estudo, determinou-se a prevalência de marcadores sorológicos para as hepatites B e C em indivíduos do Estado do Pará, atendidos no Laboratório Central de Saúde Pública do Pará, no período de janeiro de 2002 a dezembro de 2005. Foram realizados 11.282 exames para a pesquisa do HBsAg, 2.342 para o anti-HBc e 5.542 para o anti-vírus da hepatite C. A prevalência de HBsAg foi de 3,6% e predominou na faixa etária de 20 a 29 anos, enquanto que o anti-HBc foi observado em 37,7% dos indivíduos. A prevalência do antivírus da hepatite C foi de 3,6% e predominou entre indivíduos acima de 50 anos. Assim, as freqüências dos marcadores encontradas no Pará foram mais altas que em vários outros estados do país, sugerindo a necessidade de medidas de saúde publica mais eficazes no combate a estes agravos na região.

Prevalence of hepatitis B and C serological markers among first-time blood donors in Brazil: a multi-center serosurvey

Little data are available on the seroprevalence of, and risk factors for hepatitis B and C viruses (HBV and HCV) infection in Latin American countries. A multi-center serosurvey was conducted among 3,598 first-time blood donors (65% men) from Sao Paulo, Salvador and Manaus in Brazil. The gender-specific seroprevalences of antibodies against hepatitis B core antigen (anti-HBc) and of the hepatitis B surface antigen (HBsAg) in anti-HBc-positive sera were measured, and risk factors analyzed by gender. The gender-specific seroprevalences of antibodies against HCV (anti-HCV) were measured, but risk factors for HCV were not determined. Anti-HBc and HBsAg seroprevalences were not significantly different in men [101/2,341 (4.31%) and 4/2,229 (0.18%), respectively] and women [65/1,237 (5.25%) and 8/1,169 (0.68%), respectively], whereas the seroprevalence of anti-HCV was higher in women (12/1,238 [0.97%] vs. 9/2,353 [0.38%]; odds ratio [OR] = 2.49; 95% confidence interval [CI]: 1.0-6.0). No significant difference for HBV infection was found across the three study sites or by ethnic group. The seroprevalence of anti-HBc increased with age, but decreased with education level in both genders. Lifetime number of sexual partners was associated with anti-HBc prevalence among men (OR = 1.95; 95% CI: 1.2-3.1), but not women. The seroprevalence of HBV and HCV was low among Brazilian blood donors, and exposure increased with age in both genders.

Determination of hepatitis B virus DNA incidence, viral load, and mutations in blood donors with HBsAg and anti-HBs-negative serology and antibodies to hepatitis B core antigen

BACKGROUND

The aim of the present study was to determine hepatitis B virus DNA incidence, viral load, and mutations in blood donors with HBsAG and anti-HBs negative serology and antibodies to hepatitis B core antigen.

METHODS

Blood samples were collected from 1000 blood donors with HBsAg-negative test results. Anti-HBc total screening was performed using the ELISA method. HBsAg-negative/anti-HBc total-positive samples were tested for anti-HBs, anti-HBc IgM, HBeAg, and anti-HBe. Samples with isolated anti-HBc were determined for viral load of HBV DNA using real-time PCR.

RESULTS

Anti-HBc total was established as positive in 200 (20%) of the 1000 blood donors. While anti-HBs was negative in 59 (29.5%) of the 200 anti-HBc-positive samples, it was found to be positive in 141 (70.5%) of them. All of the other hepatitis B markers were negative in all of the anti-HBs-negative samples. HBV DNA was not detected in the sera of the isolated anti-HBc-positive blood donors with real-time PCR.

CONCLUSION

Although we could not detect HBV DNA in the sera of the isolated anti-HBc-positive blood donors, findings in the literature suggest that anti-HBc testing should be used in combination with HBsAg for the screening of blood donors to reduce risk. After that, the most appropriate algorithm to follow can be HBV DNA screening of donors.

Seroprevalence of hepatitis B and C virus markers among blood donors in Rio de Janeiro, Brazil, 1998-2005

The prevalence of infection by hepatitis B (HBV) and C (HCV) viruses varies among geographical regions. In order to determine the prevalence of HBV and HCV infection in voluntary blood donors we evaluated the prevalence of HBsAg, anti-HBc, and anti-HCV markers of 128,497 blood donor samples collected from 1998 to 2005 in the state of Rio de Janeiro. These markers were analyzed by immunoenzymatic tests, as determined by the Ministry of Health. Data were obtained from the Sorology Laboratory of the Hemotherapy Service of the Instituto Nacional de Câncer, Rio de Janeiro. Overall prevalence estimates were: 0.27% for HBsAg, 3.68% for anti-HBc, and 0.90% for anti-HCV. There was a significant decrease in the overall prevalence of HBsAg (from 0.36 to 0.14%) and anti-HBc (from 6.12 to 2.05%) in the period encompassed between 1998-2005. Similarly, there was a decline in anti-HCV prevalence rates in Brazilian blood donors, from 1.04% in 1998 to 0.79% in 2004, with an increase of HCV prevalence to 1.09% in 2005. These prevalence estimates were higher than those found in other countries, indicating high rates of infection by HBV and HCV and a persistent risk of HBV and HCV transmission by transfusion.

HBV vaccination of HCV-infected patients with occult HBV infection and anti-HBc-positive blood donors

Anti-HBc positivity is a frequent cause of donation rejection at blood banks. Hepatitis B virus (HBV) infection may also occur in HBsAg-negative patients, a situation denoted occult infection. Similarly, very low levels of HBV-DNA have also been found in the sera of patients with chronic hepatitis C virus (HCV) infection, even in the absence of serum HBsAg. Initially we searched for HBV-DNA in serum of 100 blood donors and 50 HCV-infected patients who were HBsAg negative/anti-HBc positive by nested-PCR and by an HBV monitor commercial test for HBV-DNA. Anti-HBs seroconversion rates were measured in 100 blood donors and in 22 patients with chronic HCV infection after HBV vaccination to determine if the HBV vaccination could eliminate an occult HBV infection in these individuals. Occult HBV infection was detected in proportionally fewer blood donors (6/100 = 6%) than chronic hepatitis C patients (12/50 = 24%) (P < 0.05). We noted seroconversion in 6/6 (100%) HBV-DNA(+) and in 84/94 (89.4%) HBV-DNA(-) blood donors (P > 0.05). All subjects who were HBV-DNA(+) before the first dose of HBV vaccine (D1), became HBV-DNA(-) after D1, D2, and D3. Among 22 HCV-positive patients, 10 HBV-DNA(+) and 12 HBV-DNA(-), seroconversion was observed in 9/10 (90%) HBV-DNA(+) and in 9/12 (75%) HBV-DNA(-) subjects (P > 0.05). The disappearance of HBV-DNA in the majority of vaccinated patients suggests that residual HBV can be eliminated in patients with occult infection.

Hepatitis B virus DNA in blood donors with anti-HBc as a possible indicator of active hepatitis B virus infection in Yucatan, Mexico

Hepatitis B virus (HBV) may be present in serum even when negative for HBV surface antigen (HBsAg). If routine screening of sera for anti-HBV core antigen (anti-HBc) is not done, low-level HBV viraemia may not be identified. A study was done on the presence of HBV DNA in serum samples from Mexican blood donors negative for HBsAg. Sera from 158 volunteer blood donors, negative for HBsAg and anti-HBs, but positive for anti-HBc, were analysed using nested polymerase chain reaction (PCR). HBV DNA was detected in sera from 13 (8.23%) of the 158. Specificity of the PCR-amplified products was corroborated using Southern blot. Single strand conformation polymorphism (SSCP) analysis showed identical SSCP-banding patterns for all 13 PCR products, suggesting similar cDNA sequences. Occult HBV infection was observed in approximately 8% of anti-HBc only donors. The absence of HBsAg in the blood of apparently healthy individuals may not be sufficient to ensure lack of circulating HBV, and blood containing anti-HBc only may be infectious until proven otherwise.

Detection of an acute asymptomatic HBsAg negative hepatitis B virus infection in a blood donor by HBV DNA testing

The issue of HBV DNA screening on blood donations is controversially discussed since the economic impact of post-transfusion hepatitis B is expected to be relatively low. We report on a case of HBsAg negative unapparent acute HBV infection, which was detected by HBV NAT testing on 96-member maxi-pools with a commercially available NAT assay, which has a detection threshold of 3 IU/mL of plasma. The presence of an HBsAg escape mutant could be excluded by sequencing the amplified DNA. Follow-up testing showed the presence of an acute HBV infection (anti-HBc-IgM positive) and finally anti-HBs seroconversion. Although the reduction of the diagnostic window with NAT screening on maxi-pools may be relatively low, it may help to improve the residual risk of blood donation, especially in asymptomatic HBV infection, where the HBsAg positive period may be very short and low levels of circulating surface antigen are present. It would also permit to detect occult HBV infection in chronic carriers who are HBsAg negative. Since the viral load in chronic isolated anti-HBc positive carriers is low, there is a potential risk for failure of HBV DNA detection with pool-PCR in blood donors. Anti-HBc screening would reduce the residual risk.

Low rate of occult hepatitis B virus infection among anti-HBc positive blood donors living in a low prevalence region in Brazil

OBJECTIVE

The aim of this study was to determine the rate of occult hepatitis B virus (HBV) infection among blood donors living in a geographic region of low (5.6%) anti-HBc prevalence.

SUBJECTS AND METHODS

Sera from 150 candidate blood donors whose blood was rejected due to total anti-HBc reactivity (despite absence of HBsAg) were tested for anti-HBs and IgM anti-HBc antibodies, as well as for HBeAg/anti-HBe. Serum HBV DNA was sought by using a PCR assay able to amplify part of the surface gene. Viral load was measured in the PCR positive samples.

RESULTS

The pattern 'anti-HBc alone' (without HBsAg and anti-HBs antibodies) was found in 64 (42.7%) subjects. IgM anti-HBc and anti-HBe antibodies were detected in 2 (1.3%) and 80 (53.3%) samples, respectively. No sample was HBeAg-reactive. HBV DNA was repeatedly found in five (3.3%) samples, three of which were anti-HBs positive and two anti-HBs negative. All five HBV DNA positive samples showed a low viral load (<1000copies/ml).

CONCLUSIONS

The data indicated a low rate of occult infection among anti-HBc positive, HBsAg negative blood donors living in a region of low prevalence of infection. Viral load was very low in all HBV infected subjects.