Hepatitis B surface antigen particles of subtypes adw and adr, and compound subtype (adwr) in symptom-free carriers in Japan

Co-Infection with Hepatitis B Virus Genotype D and Other Genotypes in Western Japan

OBJECTIVE

Genotypes B and C are the prevalent hepatitis B virus (HBV) genotypes in eastern Asia. Although very rare in this region of the world, genotype D was found to be prevalent in a small area of western Japan. In this study, we confirm the frequency and clinical significance of co-infection with different genotypes among patients from that area infected with genotype D.

METHODS

Twenty-three patients from the same area of western Japan infected with HBV genotype D, determined using a genotyping enzyme immunoassay, were studied. Cloning was done using DNA extracted from serum samples, and polymerase chain reaction assays with the restriction fragment length polymorphism for HBV genotyping were performed with 10 clones from each patient.

RESULTS

Four (17.4%) of the 23 patients were found to be co-infected with HBV genotype C, and the HB surface antigen subtype was ayw in both mono- and co-infected patients. No clinical differences were found between mono-infected and co-infected patients carrying genotype D.

CONCLUSION

A significant number of patients from the study area found to be infected with HBV genotype D were co-infected with genotype C. Additional study with a larger number of patients is needed to elucidate the possible clinical significance.

Determination of HBsAg subtypes in Western Siberian part of Russia

A set of monoclonal antibodies with specificity for hepatitis B surface antigen (HBsAg) was used for subtyping this antigen in sera from indigenous natives, blood donors, and drug users in Western Siberia with a modified commercial enzyme immunoassay kit for HBsAg detection. Three subtypes of HBsAg in a ratio of 36 (78%) ayw2:8 ayw3varB (18%):2 (4%) adw2 were found in 46 (100%) HBsAg-positive sera of different aboriginal populations of Western Siberia: the Tundra Nenets, Northern Khanty, Southern Altaians, and Kazakhs. Four subtypes of HBsAg in a ratio of 81 (57%) ayw2:58 (15 ayw3varA and 43 ayw3varB; 44%):2 (1%) adw2 were detected in 141 (100%) samples of blood donors from ten cities of Western Siberia. Three subtypes of HBsAg in a ratio of 34 ayw3:(both variants, 33 ayw3varA and 1 ayw3varB; 97.1%):1 (2.9%) ayw2 were found in blood of 35 injection drug users in Novosibirsk.

HBV subtype as a marker of the clinical course of chronic HBV infection in Japanese patients

Hepatitis B virus (HBV) genotype C is predominant in Japan. However, many HBV subtypes are involved in each genotype, and the clinical manifestations in the patients associated with each subtype remain unknown. Therefore, we investigated the relationship between HBV subtype and clinical aspects of chronic HBV infection. The subtype of 237 patients with chronic HBV infection, including 74 asymptomatic carriers, was determined. The subtypes of 110 HBV carriers undergoing long-term follow-up management were determined twice to detect subtypic changes. The clinical features of the patients were also studied with regard to presence or absence of subtypic change. The subtypic distribution in the 237 HBV carriers was as follows: subtype adr, 161 (68%); subtype adw, 25 (11%); subtype adwr, 12 (5%); subtype ar, 24 (10%); subtype adyr, 4 (2%); and unclassified, 8 (3%). The proportion of asymptomatic carriers in patients with subtype adw was significantly higher than those in patients with subtype adr (56% vs. 28%, P < 0.05). In addition, the proportion of HCC in patients with subtype adwr was significantly higher than those in patients with subtype adr (25% vs. 6%, P < 0.05). The prevalence of subtype adr in 74 asymptomatic carriers tended to decrease with age (82% in carriers aged < or =35 years vs 43% in those aged > or =61 years, P < 0.05). The subtypic change and the course of chronic HBV infection had no significant correlation. These results suggest that HBV subtypes are associated with the clinical course of chronic HBV infection.

Profile, spectrum and significance of HBV genotypes in chronic liver disease patients in the Indian subcontinent

BACKGROUND AND AIM

Certain hepatitis B virus (HBV) genotypes have been alleged to be associated with the development of cirrhosis and hepatocellular carcinoma (HCC), and the response to interferon therapy in Taiwanese patients. We undertook to study the prevalence and significance of HBV genotypes in the Indian subcontinent.

METHODS

One hundred and thirty histopathologically proven chronic HBV-infected patients, including 52 incidentally detected asymptomatic hepatitis B surface antigen (HBsAg)-positive subjects (IDAHS) with chronic HBV infection (group I), 48 cirrhotics (group II) and 30 hepatocellular carcinoma (HCC; group III) patients were studied. Hepatitis B virus genotypes were determined by using restriction fragment length polymorphism, and direct sequencing of the s gene including the 'a' determinant region.

RESULTS

Only genotypes A (46%) and D (48%) were found in the chronic HBV-infected patients. A mixed infection with genotypes A and D was seen in 6% of patients. Genotype A was found in 42, 48 and 50%, and genotype D in 48, 50 and 47% of group I, II and III patients, respectively (P = NS). The patients who had mixed genotypes were significantly younger (P < 0.05). In group I (IDAHS) patients infected with genotype D, none had a histological activity index (HAI) of < four. Genotype D was significantly more common in group I patients with HAI > 4 as compared to genotype A (53 vs 32%, P < 0.05). Similarly, genotype D was associated with more severe liver diseases (61 vs 30%, P < 0.05). Genotype D was more prevalent in HCC patients of < 40 years of age, as compared to IDAHS (63 vs 44%, P = 0.06).

CONCLUSIONS

(i) Hepatitis B virus genotypes A and D are prevalent in chronic liver disease patients of Indian origin; and (ii) HBV genotype D is associated with more severe diseases and may predict the occurrence of HCC in young patients.

Determination of hepatitis B virus subtypes by an enzyme immunoassay method using monoclonal antibodies to type-specific epitopes of HBsAg

We described a Hepatitis B surface antigen (HBsAg) subtyping method based on a commercial enzyme immunoassay (EIA) for detection of HBsAg in which the procedure was modified to include the use of monoclonal antibodies with restricted anti-HBs specificities. This method, which was able to classify HBsAg as: ayw1, ayw2, ayw3, ayw3* (intermediate between ayw3 and ayw4), ayw4, ayr, adw2, adw4 and adr, was compared to counter electrophoresis procedure (CEP) by testing HBsAg positive sera from blood donors included in a prospective national epidemiological survey. Among the 256 HBsAg positive samples tested with both techniques, 111 (43.3%) could not be subtyped with CEP vs 10 (3.9%) with our modified EIA. This difference was related to the serum HBsAg concentration which must be greater than 3000 ng/mL and 100 ng/mL for CEP and EIA, respectively. The results obtained from 145 sera with both methods were concordant. Seventeen out of 18 samples partially classified as ay with CEP were completely determined with EIA. This reliable procedure, derived from commercially available reagents, can be easily used in several applications such as large epidemiologic studies and as a substitute for nucleotide sequencing genotyping which is not adapted for large-scale screening and not applicable on samples from nonviremic hepatitis B virus (HBV) carriers.

Genotype may correlate with liver carcinogenesis and tumor characteristics in cirrhotic patients infected with hepatitis B virus subtype adw

To identify the influence of hepatitis B virus (HBV) genotype on development of hepatocellular carcinoma (HCC) and clinical outcome in chronic HBV infection, 26 consecutive cirrhotic patients infected with HBV subtype adw were investigated prospectively. HBV serology was undertaken using subtype-specific antibodies against hepatitis B surface antigens. The HBV genotype was determined by sequencing directly the polymerase chain reaction products of the HBV S gene. When HCC occurred, patients underwent transcatheter arterial embolization therapy. If tumor necrosis was incomplete, additional embolization therapy was carried out after a 3- to 4-month interval. At a median follow-up of 14.1 years (range 2.2 to 31.7), HCC occurred in 9 (35%) of 26 patients. Nineteen patients were infected with genotype B and 7 with genotype C. Four of the 19 genotype B patients (21%) and 5 of the 7 genotype C patients (71%) developed HCC (P = 0.058). Patient age (<45 years or 45 < or = ) at diagnosis of cirrhosis was the only significant independent factor influencing liver carcinogenesis by multiple logistic regression analysis and Cox's regression analysis (P = 0.0069 and 0.029, respectively). When analysis was limited to the age of 45 years or more at the last visit, genotype was the only contributory factor to HCC development by univariate analysis (P = 0.038). Whereas genotype B patients responded well to embolization therapy and had no recurrence of HCC for a prolonged period of time, genotype C patients showed poor responses and died of hepatic failure due to rapid HCC progression despite embolization therapy. The cumulative incidence of survival was significantly higher in the genotype B group (P = 0.0049). The HBV genotype correlated with the development of HCC, response to embolization therapy, and recurrence of HCC. Determination of HBV genotype may be useful in predicting outcomes in HBV subtype adw-related cirrhosis.

HBsAg subtype distribution among different populations of HBsAg carriers in Spain

Data concerning the HBsAg subtype distribution in Spain are out-of-date and confined to a restricted geographical area. Furthermore, the complex distribution observed in the countries surrounding Spain prevents any prediction. To obtain further data on HBsAg subtype distribution among Spanish HBsAg carriers, subtyping analysis (d and y determinants) was performed in 670 samples from subjects belonging to various epidemiological risk groups and coming from different geographical areas of the country. Similar frequencies were found for both mutually exclusive d/y subtype determinants among non-risk, normal HBsAg carriers from almost all geographical areas studied. In contrast, the ay subtype was clearly predominant (79-87%) among intravenous drug users, irrespective of their geographical origin. Thirteen different institutions for mentally retarded patients behaved as closed communities for HBV circulation, showing independent subtype distributions. Thus, no significant geographical variations were found for HBsAg subtype distribution in Spain. The prevalence of each particular subtype is mainly dependent on the epidemiological characteristics of the carriers studied. Subtype distribution was independent of the presence of HBeAg or HDV infection serum markers when homogeneous groups were considered separately. Atypical HBsAg phenotypes, either with coexistence or absence of both subtype determinants, were found in some cases.

Hepatitis B virus subtypes and hepatitis C virus genotypes in patients with chronic liver disease or on maintenance hemodialysis in Indonesia

Hepatitis B surface antigen (HBsAg) and hepatitis C virus (HCV) RNA were surveyed in patients in Yogyakarta, Indonesia, and their subtypes and genotypes were determined by serological methods and polymerase chain reaction with type-specific primers, respectively. Of 149 patients with chronic liver disease including 24 with chronic hepatitis, 86 with liver cirrhosis, and 39 with primary hepatocellular carcinoma, HBsAg was detected in 40 (27%) and HCV RNA in 48 (32%); one patient was positive both for HBsAg and HCV RNA. Thus, the cause of chronic liver disease was not identified in 62 (42%) patients. Of 58 patients on maintenance hemodialysis, four (7%) were positive for HBsAg and 44 (76%) for HCV RNA. Subtype adw was found in 34 (74%) of 46 HBsAg samples and adr in five (11%); compound subtypes, such as adyw and adyr were detected in the remaining seven (15%). Among HCV RNA samples from 48 patients with chronic liver disease, 23 (48%) were of genotype II, 17 (35%) of genotype III and one (2%) of genotype V, in a distribution strikingly different from that of 44 samples from patients on maintenance hemodialysis, 39 (89%) of which were of genotype I and only one (2%) of genotype II. Genotypes were not classifiable in seven (15%) patients with liver disease and four (9%) patients on hemodialysis despite high HCV RNA titers in them all. These results indicate that different HCV genotypes prevail in patients with distinct diseases, as well as unclassifiable HCV genotypes in Indonesia.

Polymerase chain reaction can resolve some undefined cases of hepatitis B virus antigenic subtyping

HBsAg subtypes were defined by means of adsorbed polyclonal antisera; however, HBsAg subtyping is currently usually carried out with monoclonal antibodies (Mab). We developed a complementary subtyping method based on the polymerase chain reaction. Reference samples belonging to all known HBsAg subtypes could be detected and grouped into four different categories (ayw1/ayw4/ayr, ayw2/ayw3, adw2/adrq+/adrq-, adw4). Thirteen HBsAg-positive serum samples previously subtyped as ad by means of monoclonal antibodies fell into the adw2/adrq+/adrq- group, as well as 13 ay samples into the ayw2/ayw3 group. These results could be confirmed by means of reference polyclonal antisera in nine ad cases (all adw2) and in seven ay cases (all ayw3); the remaining seven were below the detection limit of the polyclonal assay. Four samples which were not recognized by any of the d/y subtype-specific Mab were shown to contain ayw2/ayw3 sequences. Only one contained sufficient HBsAg to be confirmed as ayw3 by means of reference antisera. Three of five sera showing simultaneous reactivity both for d and y-specific Mab were classified as adw4 by PCR, as was one by reference polyclonal antisera. The y-specific monoclonal antibody cross-reacted with the adw4 subtype. Single adw2 sequences were amplified in one of the remaining two cases, as well as single ayw2/ayw3 sequences in the other, suggesting that they showed true coexistence of two strains of different subtype, only one of which was in active replication state. It is concluded that the method described is useful in the solution of some undefined cases obtained with the monoclonal-based assays.