Absence of hepatitis B virus DNA detected by polymerase chain reaction in blood donors who are hepatitis B surface antigen negative and antibody to hepatitis B core antigen positive from a United States population with a low prevalence of hepatitis B serologic markers

A recent study in hepatitis B surface antigen (HBsAg)-negative, antibody to hepatitis B core antigen (anti-HBc)-positive blood donors from a population with a high prevalence of hepatitis B serologic markers showed the presence of hepatitis B virus DNA (HBV DNA) as detected by polymerase chain reaction (PCR) in 4 percent of these donors. A sensitive, nested PCR assay was used to assess the prevalence of HBV DNA in a population of HBsAg-negative, anti-HBc-positive blood donors from a United States population with a low prevalence of hepatitis B serologic markers. The lower limit for detection by the PCR assay was 10(-5) pg per mL of HBV DNA. There was a review of 26,492 consecutive blood donations in a 12-month period. During this time, only 1 unit (0.004%) was HBsAg positive. An additional 158 units (0.6%) were repeatably reactive for anti-HBc. These 158 HBsAg-negative, anti- HBc-positive units were given by 119 donors of blood for allogeneic and autologous use. HBV DNA was not detected by PCR in blood from 83 allogeneic blood donors (93 samples) or 36 autologous blood donors (65 samples). Anti-HBc testing is an inefficient means of screening for potential hepatitis B infectivity and is associated with low test specificity in populations with a low prevalence of hepatitis B serologic markers.     

The clinical features of chronic hepatitis C are not affected by the coexistence of hepatitis B virus DNA in patients negative for hepatitis B surface antigen

Hepatitis B virus (HBV) DNA has been detected in the sera of hepatitis patients who are negative for hepatitis B surface antigen (HBsAg) by polymerase chain reaction (PCR). The purpose of the present study was to clarify the clinical characteristics of patients with chronic hepatitis C who are negative for serum HBsAg and positive for HBV DNA. The subjects included 49 patients with chronic hepatitis C who were negative for serum HBsAg and 119 blood donors who served as healthy controls. Serum samples were tested for the presence of HBV DNA by the nested PCR method. Serum HBV DNA was detected in 18 (37.7%) of the 49 chronic hepatitis C patients and in none (0%) of the 119 blood donors. Among the hepatitis C patients, HBV DNA was detected in 20.7% of those who were negative for all HBV-associated markers and in 57.1% of those who were positive for one or more HBV-associated marker. The HBV DNA-positive rate among those in each F stage did not significantly differ. The liver function parameters of the HBV DNA-positive and the HBV DNA-negative chronic hepatitis C patients did not significantly differ. These results suggest that hepatitis C virus is frequently coinfected with serum HBsAg-negative HBV, and that the incidence of HBV infection in blood donors is low. However, it is considered that HBsAg-negative HBV infection does not modify the blood biochemical features of chronic hepatitis C.     

上海地区献血人群隐匿性HBV感染状况

目的 了解HBsAg阴性、抗-HBc阳性的献血人群中HBV DNA感染情况.方法采用酶联免疫法(ELISA)检测5 121份HBsAg阴性的合格献血者血清抗-HBc和抗-HBc阳性反应滴度;对抗-HBc阳性样本采用ELISA法检测血清抗-HBs,采用巢式PCR三区段扩增法检测HBV DNA.结果HBsAg阴性的献血人群...     

Frequent presence of HBV in the sera of HBsAg-negative, anti-HBc-positive blood donors

BACKGROUND: Recent studies have revealed that HBV may not be cleared even after the disappearance of serum HBsAg. The purpose of this study was to investigate whether the replication of HBV persists in HBsAg-negative blood donors who lack apparent liver disease. STUDY DESIGN AND METHODS: Serum HBV was examined by using PCR coupled with Southern blotting in 50 blood donors who were identified to be HBsAg negative but anti-HBc positive. RESULTS: HBV DNA was detected in the sera from 19 (38%) of 50 donors. In 11 of the 19, HBV existed exclusively as immune complexes, while HBV presumably did not exist as immune complexes in the remaining eight. The levels of HBV DNA were similar to those in patients who had recovered from acute HBV. Some nucleotide substitutions, which did not confer amino acid changes in the major epitope of HBsAg, were found in the preS-S regions. CONCLUSION: The replication of HBV is ongoing in a substantial proportion of healthy blood donors who have anti-HBc. Blood from such donors may contain very low levels of HBV free of immune complex formation and should be excluded for transfusion. The fact that such blood donors apparently lacked liver disease suggests no pathogenicity of such "occult" HBV.     

Donor screening for antibody to hepatitis B core antigen and hepatitis B virus infection in transfusion recipients

BACKGROUND: Testing for antibody to hepatitis B core antigen (anti-HBc) as a surrogate for hepatitis C viremia is no longer needed for blood donor screening. Currently, the important question is how much its use supplements hepatitis B surface antigen (HBsAg) donor screening in preventing transfusion-transmitted hepatitis B virus (HBV) infection. STUDY DESIGN AND METHODS: In a study conducted in the 1970s, 64 blood donors were associated with 15 cases of HBV (1.0%) in 1533 transfusion recipients. Sera from 61 donors at donation and 29 follow-up visits were available for present-day assays for HBsAg, HBV DNA, anti-HBc, and antibody to HBsAg (anti-HBs). RESULTS: HBsAg was found in four previously negative blood donors; HBV DNA was limited to three of these four. Anti-HBc was detected in six HBsAg-negative donors. Two other donors were negative in all assays at donation, but positive for anti- HBc and anti-HBs 2 to 4 months later. The remaining donors were negative for all HBV markers, which left five recipient cases unexplained. No HBV transmission was observed when anti-HBs sample-to- negative control values were > or = 10. CONCLUSION: Some 33 to 50 percent of cases of hepatitis B that could be transmitted by transfusion of blood from HBsAg-negative donors are prevented by anti- HBc screening. Anti-HBc-positive donors unequivocally positive for anti- HBs should be considered noninfectious for HBV and should be allowed to donate. Anti-HBc screening of paid plasmapheresis donors, supplemented by anti-HBs testing, would reduce the amount of HBV to be processed by virus inactivation and increase the content of anti-HBs in plasma pools.     

Prevalence of Occult Hepatitis B Virus Infection in Blood Donors with Negative ID-NAT in Switzerland

IntroductionScreening of hepatitis B surface antigen (HBsAg) and individual-donation nucleic acid amplification testing (ID-NAT) of blood donors have become standard to detect hepatitis B virus (HBV) infection. However, there is still a residual risk of HBV transmission by blood components of donors suffering from occult HBV infection (OBI). Therefore, many countries implemented universal testing of anti-HBV core antigen (anti-HBc) antibodies in order to increase blood safety. In Switzerland, anti-HBc testing is not part of the routine blood donor-screening repertoire. Therefore, we sought to assess prevalence of donors with OBI in a Swiss blood donor collective.MethodsBlood donations were prospectively investigated for the presence of anti-HBc antibodies during two time periods (I: all donors, March 2017; II: first-time donors only, April 2017 until February 2018). Anti-HBc-positive findings were confirmed by an anti-HBc neutralization test. Discarded plasma samples of anti-HBc-confirmed positive donors were ultracentrifuged and subsequently retested by regular HBV-ID-NAT to search for traces of HBV.ResultsDuring time period I, 78 (1.6%) individuals out of 4,923 donors were confirmed anti-HBc-positive. Sixty-nine (88%) anti-HBc-positive samples were available and processed by ultracentrifugation followed by repeat HBV-ID-NAT. Four samples (5.8%) were found positive for HBV DNA. Sixty-five (94.2%) samples remained HBV NAT-negative upon ultracentrifugation. During time period II, 56 (0.9%) donor samples out of 6,509 exhibited anti-HBc-confirmed positive. Fifty-five (98%) samples could be reassessed by HBV-ID-NAT upon ultracentrifugation. Three (5.5%) samples contained HBV DNA and 52 (94.5%) samples remained HBV NAT-negative.ConclusionOverall, we detected 7 viremic OBI carriers among 11,432 blood donors, which tested negative for HBV by standard HBV-ID-NAT and HBsAg screening. In contrast, OBI carriers showed positive anti-HBc findings which could be confirmed in 83.8% of the cases. Thus, OBI might be missed by the current HBV screening process of Swiss blood donors. We suggest to review current HBV screening algorithm. Extended donor screening by anti-HBc testing may unmask OBI carriers and contribute to blood safety for the recipient of blood products.     

Infectivity of blood from PCR-positive, HBsAg-negative, anti-HBs-positive cases of resolved hepatitis B infection

BACKGROUND: Numerous reports have noted the existence of sera, particularly from resolving cases of HBV infection, that are positive for HBV DNA by PCR, despite being negative for HBsAg and IgM anti-HBc. If such blood is infective and detectable by HBV NAT screening, it seems desirable to introduce such screening for transfused blood. STUDY DESIGN AND METHODS: Three chimpanzees were inoculated with serum and lymphocytes from three patients who were HBV DNA PCR positive, but HBsAg negative. The animals were tested over a period of 15 months for HBsAg, anti-HBs, anti-HBc, and HBV DNA by PCR. RESULTS: All animals remained uninfected. CONCLUSION: Small amounts of plasma and MNCs from HBV DNA-positive HBsAg-negative blood do not appear to be infectious; however, further studies with larger volumes of inoculum should be conducted.     

Hepatitis B core antibody screening of voluntary blood donors: an extended pilot study using a modified passive haemagglutination assay

Summary. Screening for hepatitis B surface antigen (HBsAg), even by the most sensitive techniques, fails to detect all carriers of the hepatitis B virus (HBV). The presence of hepatitis B core antibody (anti-HBc) in the absence of HBsAg is a common finding in donors implicated in cases of post-transfusion hepatitis B (PTHB), and viral DNA may also be demonstrated in many of these individuals. An extended pilot study of routine screening of all donations for anti-HBc in addition to HBsAg was introduced into the Mersey and North Wales Regional Transfusion Service in November 1991 to improve surveillance for carriers of HBV. In order to reduce costs a modified passive haemagglutination assay was evaluated and found to have a sensitivity of 99% and specificity of 98% compared with a conventional assay. In the first 6 months 60 530 donations were tested and 12 (0–02%) were found to have anti-HBc in the absence of HBsAg or adequate antibodies to HBsAg (anti-HBs). These sera will later be submitted for polymerase chain reaction (PCR) testing in order to determine their infectivity or otherwise by the detection HBV DNA sequences.     

青岛地区无偿献血者乙型肝炎病毒感染血清学和病毒特征分析

目的 分析青岛地区无偿献血者乙型肝炎病毒感染的血清学及病毒学特征.方法 采用常规的血清学试验和核酸扩增技术对本地区315 520份无偿献血者标本进行联合筛查,对HBsAg-/HBV DNA+标本进行高精度病毒载量检测和补充乙肝5项检测,采用PCR直接测序法获得标本中HBsAg编码基因即S基因序列,分析病毒基因型别及氨基...     

Hepatitis-B virus markers in patients with bleeding disorders and in healthy blood donors

Sera from 113 multiply transfused patients with bleeding disorders of whom 92 (81.4 per cent) were hemophiliacs were tested for such hepatitis-B virus (HBV) markers as HBsAg, anti-HBs. anti-HBc, e-antigen and anti-e. For comparison these marker tests were conducted on sera from 398 apparently healthy blood donors, 198 were previously known to be both HBsAg and anti-HBs negative, 126 were anti-HBs positive and 74 were HBsAg positive. Among patients with bleeding disorders, overt HBV infections were infrequent (2 per cent) and there was a low prevalence of HBsAg (3.5 per cent), e-antigen (1 per cent) and anti-e (0 per cent). However, the prevalence of anti-HBs (63 per cent) and anti-HBc (55 per cent) was high. Of the 71 anti-HBs positive patients with bleeding disorders 54 (76 per cent) were also anti-HBc positive. The sera of only four patients contained anti-HBc alone. All but one of the patients with bleeding disorders who were anti-HBc positive exhibited persistent responses. Anti-HBc was detected in all the HBsAg positive blood donors and in 113 of 126 (90 per cent) of those who were anti-HBs positive, but in none who were HBsAg and anti-HBs negative. The highest titers of anti-HBc, both among blood donors and patients with bleeding disorders occurred in those who were HBsAg positive. Among patients who were both anti-HBs and anti-HBc positive, highest anti-HBc titers occurred in those aged 31 to 40. Anti-e was detected in 59 per cent of HBsAg positive and 5 per cent of anti-HBs positive blood donors, but e-antigen was detected in none.     

Transfusion-transmitted HBV infection in an endemic area: the necessity of more sensitive screening for HBV carriers

BACKGROUND: By NAT, HBV DNA is occasionally detectable in blood donors with past HBV infection but negative for HBsAg. Whether or not these donors can cause transfusion-transmitted HBV infections is uncertain. STUDY DESIGN AND METHODS: To determine whether or not donors with past HBV infection but negative for HbsAg can cause HBV transfusion-transmitted infections, recipients followed for blood transfusion in a university medical center in Taiwan were studied. HBV DNA and serologic markers were tested in donors and recipients. RESULTS: Of 1,038 enrolled recipients, 910 completed the 6-month post-transfusion follow-up visit. Of these, only 39 patients (4.3%) tested negative on the pretransfusion sample for HBsAg, anti-HBs, anti-HBc, and HBV DNA by PCR. These 39 HBV-naive recipients had been transfused with blood from 147 donations for which stored samples were available for HBV DNA testing by PCR; 11 of these HBsAg-negative samples tested positive for HBV DNA and anti-HBc. Two of the 11 patients who received the HBV-DNA-positive donations (18%) became positive for HBV DNA, and one seroconverted to anti-HBc and finally to anti-HBs, with a mild transient elevation of serum ALT activities. Based on the one confirmed case of HBV transmission, a projection was made that approximately 200 post-transfusion HBV infections could occur in one million units of transfused blood in Taiwan. CONCLUSIONS: In HBV-endemic areas like Taiwan, where blood donors are screened for HBsAg only, the risk of transfusion-transmitted HBV appears to be substantial. Implementation of NAT for blood screening in these settings warrants consideration.     

Feasibility and usefulness of an efficient anti-HBc screening programme in blood donors

SUMMARY. Post-transfusion hepatitis B remains a risk for recipients of hepatitis B surface antigen (HBsAg) screened blood. Anti-hepatitis B core antibody (anti-HBc) screening may help reduce this risk. To evaluate its usefulness, 9,238 East Anglian blood donors were screened for anti-HBc. Those with isolated anti-HBc were identified with two confirmatory anti-HBc and anti-HB surface antibody (anti-HBs) assays. The prevalence of anti-HBc reactions in screening and confirmatory assays was 1.29% and 0.35%, respectively. The level of reactivity was significantly higher when two anti-HBc assays gave concordant results or, being concordant, were anti-HBs positive. All isolated anti-HBc-positive units (0.04%) were negative for additional HBV markers including DNA tested with nested polymerase chain reaction (PCR).
A 0.31% prevalence of past HBV infection was found in this population, all carrying both anti-HBc and anti-HBs antibody, most above the protective level (0.IU/ml).
The proposed screening schemes would limit the number of deferred donors and discarded units and keep the testing time within the remit of routine blood banking practices for an additional cost of approximately £1 per unit. However, no evidence was found in this donor population to suggest that anti-HBc screening would significantly reduce the incidence of post-transfusion hepatitis B.     

Frequency of hepatitis B virus DNA in anti-HBc positive, HBsAg negative blood donors in Rasht, northern Iran

Background

One of the important factors in the ensuing safety of blood transfusion is to use a sensitive screening assay for detection of blood-born infective agents such as HBV which transmits through transfusion. To improve the detection rate of HBV infection in blood donors, a cross-sectional study was conducted in Rasht, which is the largest city in the north of Iran to explore the possibility of using anti-HBc as a screening test.

Study design and methods

A total of 2041 blood samples negative for HBsAg, Anti-HCV, Anti-HIV I, II and RPR were tested to detect anti-HBc and then the positive anti-HBc samples were further checked for the presence of HBV DNA.

Results

The prevalence of anti-HBc positive samples was 3.8% and HBV DNA was detected in only one sample.

Conclusions

This study showed that anti-HBc positive blood donors may be a source of HBV transmission and further study for evaluation of HBV DNA in anti-HBc positive blood units is needed.     

临产妇前S1抗原与乙型肝炎“两对半”联合检测的意义

目的探讨临产妇前S1抗原和乙型肝炎“两对半”组合模式的关系及其临床意义。方法用酶联免疫吸附试验（ELISA）法检测394例临产妇血清乙型肝炎病毒前S1抗原（PreS1）、乙型肝炎病毒表面抗原（HBsAg）、乙型肝炎病毒表面抗体（抗-HBs）、乙型肝炎病毒e抗原（HBeAg）、乙型肝炎病毒e抗体（抗-HBe）和乙型肝炎病毒核心抗体（抗-HBc）6种免疫指标的表达。结果HBsAg阳性血清141例，PreS1 99例（70.2％）。其中HBeAg阳性44例，PreS1检出39例（88.6％）；HBeAg阴性97例，PreS1检出60例（61．9％），两者比较差异有统计学意义（χ^2=10，38，P〈0．005）。HBsAg阴性血清中未检出PreS1。结论PreS1与HBeAg具有较好的相关性，是乙型肝炎病毒复制的可靠指标之一，与乙型肝炎“两对半”联合检测可更准确反映乙型肝炎病毒感染复制状况。     

Infectivity of blood components with low hepatitis B virus DNA levels identified in a lookback program

BACKGROUND: Japanese Red Cross (JRC) blood centers implemented anti-hepatitis B core antigen (HBc) screening in 1989 and 50-minipool (MP)-nucleic acid testing (NAT) in 2000. A systematic lookback study has been conducted to determine the hepatitis B virus (HBV) transmission risk of donations drawn in the pre-hepatitis B surface antigen (HBsAg) and/or MP-NAT window phase and by donors with occult HBV infection. STUDY DESIGN AND METHODS: JRC blood centers have been storing aliquots of every blood donation since 1996. On the basis of the complete repository tube archives, all donations from repeat donors received from 1997 to 2004 were subjected to a lookback study. When repeat donors turned positive for HBV viral marker(s), repository tubes from their previous donations were tested for HBV with individual-donation (ID)-NAT. The frequency of ID-NAT-only-positive donations and the HBV transmission risk by the transfusion of those components were investigated. RESULTS: HBV ID-NAT was performed on 15,721 repository tubes, and 158 tubes (1.01%) were found positive for the presence of HBV DNA. Of these 158 ID-NAT-only-positive donations, 95 (60%) were derived from carriers with low anti-HBc titers. Of 63 patients transfused with ID-NAT-only-positive components, 12 (19%) proved to be infected with HBV. Only 1 of 33 components with low anti-HBc titers could be identified as infectious, whereas 11 of 22 anti-HBc-negative components proved to be infectious. None of the 16 identified hepatitis B surface antibody-positive components showed serologic evidence of infection. CONCLUSION: The clinically observed HBV infection risk caused by blood components from occult HBV carriers with low anti-HBc titers who slip through the JRC screening system is more than 10-fold lower than the transmission risk by donations in the pre-HBsAg and/or MP-NAT window phase.     

Long-term presence of HBV in the sera of chronic hepatitis B patients with HBsAg seroclearance

OBJECTS: The aim of this study was to elucidate the presence of serum hepatitis B virus (HBV) DNA at a prolonged time after seroclearance of hepatitis B surface antigen (HBsAg). METHODS: Seventy Japanese patients who had been observed for >5 years after HBsAg seroclearance were included in this study. Anti-HBs, anti-HBe and anti-HBc antibodies were measured 0, 5 and 10 years after HBsAg seroclearance. Serum HBV DNA was measured using nested polymerase chain reaction (PCR) at 0, 5 and 10 years after HBsAg seroclearance. The PCR detection of serum HBV DNA using the X gene and core gene primers was done. The HBV DNA was regarded as positive when PCR detection of HBV DNA using either or both the X gene and core gene primers was positive. A multivariate regression analysis was used to assess the factors contributing to the positivity of serum HBV DNA 5 years after HBsAg seroclearance: the factors examined included age, gender, histological findings, HBV genotype, aminotransferase, total protein and interferon administration. RESULTS: The titers of 200-fold diluted serum anti-HBc were 6.5 +/- 4.0 at 0 year after HBsAg seroclearance, 1.8 +/- 1.4 at 5 years and 0.9 +/- 0.7 at 10 years. The titers of 200-fold diluted serum anti-HBc decreased 5 and 10 years after HBsAg seroclearance with statistical significance. The positive rate of HBV DNA by the nested PCR was 71.4% (50/70) at 0 year after HBsAg seroclearance, 21.4% (15/70) at 5 years and 14.3% (3/21) at 10 years. However, there were no significant factors contributing to the positivity of serum HBV DNA 5 years after HBsAg seroclearance. CONCLUSION: Our results suggest that serum HBV DNA disappears with an incidence of 10-20% 5 and 10 years after HBsAg seroclearance.     

Hepatitis B core antigen antibody as an indicator of a low grade carrier state for hepatitis B virus in a Saudi Arabian blood donor population

Blood donor screening for anti-hepatitis B core antigen (anti-HBc) was introduced as a surrogate marker of non-A, non-B hepatitis prior to the availability of a specific test for hepatitis C. In areas endemic for hepatitis B virus (HBV), such as Saudi Arabia, earlier studies indicated that up to 30% of blood donors might disqualify if screened for anti-HBc. The issue was readdressed in a study of 6035 consecutive first-time Saudi national blood donors in an attempt to identify a subgroup of anti-HBc positive donors who might be at high risk of being low grade carriers of HBV. An isolated anti-HBc of high titer in a donor with a low or absent anti-hepatitis B surface antigen (anti-HBsAg) was taken as an indicator of increased risk of a low grade carrier state. Using this algorithm, an additional 125 (2%) donors would disqualify. HBsAg immune complex assays and polymerase chain reaction of donor samples with an isolated anti-HBc identified two donors with immune complexes and two donors with HBV DNA. All four donor samples expressed over 90% neutralization in the anti-HBc supplementary testing, indicating high titer anti-HBc. These findings seem to support the suggested policy of donor exclusion based on the anti-HBc and anti-HBsAg serology as a means to eliminate low grade carriers of HBV in endemic areas without jeopardizing the blood supply.     

Anti-HBc screening in Egyptian blood donors reduces the risk of hepatitis B virus transmission

summary .  Occult hepatitis B virus (HBV) in blood donors is considered as a potential risk for transmission of HBV infection. The aim of this study was to determine the prevalence of anti-hepatitis B core antibody (anti-HBC) positivity in Egyptian blood donations as well as to estimate the frequency of HBV-DNA in anti-HBc-positive donations. The study included 760 Egyptian healthy blood donors, representing 26 different Egyptian governorates screened according to routine practice for the presence of hepatitis B surface antigen (HBsAg), hepatitis C virus (HCV) antibodies (Abs), HIV-1/2 Abs and Treponema Abs. The accepted blood units for donation were tested for the presence of total anti-HBc Abs by two tests. Positive units for anti-HBc were further tested for HBV-DNA by polymerase chain reaction. According to routine screening, a total of 48/760 units (6·3%) were rejected [38 (5%) HCV-Ab-positive units, 9 (1·18%) HbsAg-positive units and 1 (0·13%) Treponema-Ab-positive unit]. Among the accepted blood units for donation, prevalence of anti-HBc was 78/712 units (10·96%). HBV-DNA was detected in 9/78 (11·54%) of the anti-HBc-positive units, and thus, occult HBV infection was detected in 9/712 (1·26%) of the accepted blood donations. Implementing anti-HBc test to the routine assay for the forthcoming two decades would certainly eliminate possible HBV-infected units. Rejection of these units will be beneficial to decrease the risk of HBV transmission with its potential consequences particularly in immunocompromised recipients.     

Liver transplantation-associated de novo hepatitis B virus infection: application of molecular evolutionary analysis

OBJECTIVE: De novo hepatitis B virus (HBV) infection after liver transplantation has recently been reported to be associated with donors without serum hepatitis B surface antigen (HbsAg) but with hepatitis B core antigen (anti-HBc). We elucidate the source of de novo HBV infection after liver transplantation by molecular evolutionary analysis. METHODS: The serum sample was obtained from a recipient who underwent living related liver transplantation. He was negative for all HBV-related serum markers before the transplantation. The recipient became seropositive for HBsAg at 6 months after transplantation. The liver tissue was obtained from a donor who was seronegative for HBsAg, but positive for anti-HBs and anti-HBc. RESULTS: HBV DNA was detected from the serum and liver tissue in a recipient and donor, respectively. A total of 5 clones each of small-S gene of HBV from the donor and recipient were sequenced. A phylogenetic tree analysis based on small-S gene revealed that all isolates derived from the recipient and donor were clustered together within a close range of evolutionary distances. These results indicated that HBV was transmitted by the liver graft from the donor. CONCLUSIONS: Molecular evolutionary analysis can be adopted for the study of the transmission route of viral infection via organ transplantation.