Human and swine hepatitis E viruses from Western India belong to different genotypes

BACKGROUND/AIMS

Hepatitis E is endemic in India. Earlier, we showed prevalence of IgG antibodies to hepatitis E virus (IgG-anti-HEV) in different animal species and inability of at least one human hepatitis E virus (HEV) strain to infect pigs. In the US where hepatitis E is not endemic in humans, zoonotic spread of HEV was suspected as swine and human HEV were closely related and cross-species infection was documented. The present study attempts to identify and partially characterize swine HEV from India.

METHODS

Serum samples from 284 pigs were screened for the presence of HEV-RNA (nested polymerase chain reaction; PCR) and IgG-anti-HEV (enzyme-linked immunosorbent assay; ELISA). PCR products (Open Reading Frame-2 region) were sequenced and subjected to phylogenetic analysis. Two sero-negative pigs were inoculated with swine HEV-positive serum pool.

RESULTS

ELISA and PCR positivity were 42.9 and 4.6%, respectively. All Indian swine HEV sequences clustered with genotype IV. Pigs could be experimentally infected with swine HEV.

CONCLUSIONS

Swine HEV circulates in Indian pigs. In contrast to US and Taiwan wherein both human and swine HEV isolates belong to same genotype, Indian human HEV isolates belong to genotype I whereas genotype IV circulates in swine. Though experimental infection with Indian swine HEV was possible, at least one human HEV strain could not infect pigs.

Seroepidemiology of influenza in Pune, India

BACKGROUND & OBJECTIVES

Influenza viruses cause frequent epidemics and periodic pandemics throughout the world due to antigenic variations. Serological data can be useful to determine the disease burden and population immunity and for predicting the likelihood of occurrence and potential severity of subsequent epidemics. We undertook a serological analysis of antibodies against ten influenza virus strains in Pune, India.

METHODS

Haemagglutination inhibition (HI) test was done on 619 sera collected between 1997-99 during an age-stratified serosurvey in Pune, India against 10 strains of influenza virus. Overall prevalence and spectrum of HI antibodies against these strains was determined.

RESULTS

Antibodies to at least one influenza virus strain was seen in 62 per cent (116/188) of the sera from individuals in the age group 5-15 yr, 77 per cent (85/111) in sera from 16-25 yr, 78 per cent (93/119) from 26-35 yr, 84 per cent (77/92) from 36-45 yr and 93 per cent (101/109) in sera from individuals aged > 45 yr. The antibody spectrum progressively increased with age. Antibodies to the pandemic strain A(H2N2) were absent in the age groups < 25 yr.

INTERPRETATION & CONCLUSION

The results indicate that influenza virus infection occurs in a large proportion of individuals in our community and may be responsible for a considerable amount of morbidity and mortality. The study also demonstrates the absence of antibody to A/Singapore/1/57 (H2N2) strain in younger persons < 25 yr of age. The potential of its reintroduction cannot be ruled out as H2 variants are circulating in wild birds and population immunity in humans is decreasing.

Changing epidemiology of hepatitis A and hepatitis E in urban and rural India (1982-98)

The epidemiology of hepatitis A virus (HAV) and hepatitis E virus (HEV) was assessed among age-stratified urban high socioeconomic, lower middle socioeconomic status and rural populations from western India in 1998. When compared with previous surveys, a clear shift from high to intermediate endemicity of HAV was evident only for higher socioeconomic population (1982-98), raising the possibility of outbreaks of hepatitis A in this category. A decrease in anti-HAV positivity was noted in rural children aged 6-10 years. Lower circulation of HEV was noted among < 25-year-old urban higher socioeconomic and rural individuals. For both viruses, the lower middle socioeconomic populations were comparable in 1982 and 1998. Socioeconomic status and family size (odds ratio = 23 and 1.6, respectively) were independently associated with anti-HAV positivity. Age, lower middle socioeconomic status and well water were significant independent variables for HEV infection (odds ratio = 5.7, 2.4 and 1.9, respectively). Hence, vaccination policy for hepatitis A needs to be reviewed.

Hepatitis G virus infection in India: prevalence and phylogenetic analysis based on 5' non-coding region

OBJECTIVES

To determine the prevalence of hepatitis G virus (HGV) infection in western India and to carry out phylogenetic analysis of HGV isolates.

METHODS

Reverse transcription-polymerase chain reaction (RT-PCR) assay was used to detect HGV RNA in serum samples obtained from paid plasma donors, patients with hemophilia and voluntary blood donors. Nine Indian and one Kenyan HGV RNA-positive samples were sequenced in the 5' non-coding region (5'-NCR). Phylogenetic analysis based on the comparison of a 101 nucleotide fragment from a large number of HGV isolates from 22 countries (including Indian and Kenyan sequences obtained during the present study) was carried out.

RESULTS

HGV RNA positivity rates among paid plasma donors from a commercial plasmapheresis unit (7/43, 16.3%) and patients with hemophilia (5/44, 11.4%) were significantly higher than that in voluntary blood donors (0/51; p=0.003 and 0.019, respectively). Among patients with acute non-A to E hepatitis and fulminant hepatic failure, 1 of 50 and 1 of 28 were HGV RNA-positive, whereas 6 of 49 (12%) patients with chronic liver disease had circulating HGV RNA. All Indian isolates belonged to genotype 2, whereas the Kenyan isolate formed a distinct branch within genotype 1 consisting of African isolates.

CONCLUSION

Our results suggest existence of parenteral transmission of HGV in the Indian population. HGV was not an important cause of acute non-A to E hepatitis or fulminant hepatic failure among the patients investigated. Genotype 2 seems to be the most prevalent genotype in western India.

Use of filter paper disks for hepatitis A surveillance

BACKGROUND

Venous blood collection is a cumbersome and uncomfortable procedure during hepatitis A surveillance. Collection of capillary blood by finger prick is an alternative method.

AIM

To evaluate the reactivity of capillary blood/anti-hepatitis A virus (HAV) IgG stored on filter paper disks for detection of anti-HAV antibody.

METHODS

Venous blood specimens were collected from healthy individuals. Simultaneous capillary blood specimens obtained by finger prick were stored on filter paper disks. A reference standard of anti-HAV IgG in known concentrations was spotted on filter paper disks. The reactivities of anti-HAV IgG and capillary blood specimens eluted from filter paper disks were tested by blocking ELISA for detection of anti-HAV antibody. The results were evaluated by comparing optical density (OD) and neutralization values with those obtained for WHO anti-HAV IgG stored in liquid phase and homologous venous blood specimens, respectively.

RESULTS

Among both venous and capillary-blood specimens stored for 10 days, percent neutralization shown by the same 46 specimens was > 50 and that of the same 3 specimens was < 50, indicating anti-HAV positivity and negativity, respectively. There was significant correlation between the OD values displayed by anti-HAV IgG from liquid phase and that eluted from filter paper disk (p < 0.01). Sixteen serum specimens stored for a period of 2 months showed results similar to those of the corresponding filter paper disk elutes.

CONCLUSION

Use of filter paper disks could be a suitable choice for pre- and post-immunization collection of blood specimens during hepatitis A surveillance.

Ten-year serological follow up of hepatitis B vaccine recipients

AIM

To determine long-term persistence of antibodies to hepatitis B surface antigen (anti-HBs) after vaccination against hepatitis B.

METHODS

Thirty-four laboratory workers received hepatitis B vaccine in 1989 in a 0-1-6 month vaccination schedule. Group A (n = 16) received a booster at 3 years after vaccination whereas Group B (n = 18) did not. Anti-HBs was quantitated at 1 month and 1, 2, 3, 5, 6 and 8 years post-vaccination.

RESULTS

At eight-year follow up, 10 of 15 subjects in Group A and 3 of 16 in Group B had protective levels of anti-HBs; in addition, two and four subjects, respectively, had detectable anti-HBs though below protective levels. At ten years, 9/15 and 3/16 were anti-HBs positive in Groups A and B, respectively. One subject in each group had rise in anti-HBs titer at 6-year follow up but both of them tested negative for IgG antibodies to hepatitis B core antigen (anti-HBc). A booster dose at 10 years to anti-HBs negative subjects led to an anamestic response in 3/4 and 8/10 persons in Groups A and B, respectively.

CONCLUSION

Immunological memory after vaccination against hepatitis B is maintained for at least 10 years.

Prevalence and phylogenetic analysis of TT virus DNA in Western India

In western India, TT virus (TTV) DNA positivity varied from 6.7% (5 of 75) in chronic hepatitis patients to 24.4% (10 of 41) in hemophiliacs; 7.4% (4 of 54) of voluntary blood donors had circulating TTV DNA. Phylogenetic analysis revealed a predominance of genotype 1a. In India, TTV is transmitted mainly by nonparenteral routes and is not an important cause of chronic liver diseases.

Epidemic hepatitis E: serological evidence for lack of intrafamilial spread

INTRODUCTION

Hepatitis E presents as epidemic as well as sporadic disease. Fecal contamination of drinking water results in epidemics of hepatitis E. The extent of intrafamilial spread needs to be assessed employing serological assays.

AIMS

To understand the dynamics of intrafamilial spread of the disease.

METHODS

The study was conducted using blood samples collected during the 1988 and 1989 epidemics of viral hepatitis in Kudal and Atit villages of Maharashtra state; the epidemics were subsequently shown to be due to hepatitis E virus (HEV). The one-time collection carried out at the end of the Kudal epidemic was from 184 apparently healthy individuals irrespective of family history of jaundice during the epidemic. In the Atit epidemic, 153 family contacts of 49 IgM anti-HEV positive patients were bled. An additional 151 blood samples were collected from apparently healthy individuals irrespective of family history of jaundice during the epidemic. One month later, blood samples were collected from 64 of the 153 family contacts. Relevant history was recorded each time. All serum samples were tested for ALT levels and for IgM and IgG antibodies to hepatitis E virus employing ELISA.

RESULTS

IgM anti-HEV positivity among persons with family history of jaundice was not different from those without such a history (8/62 [12.9%] and 11/122 [9%] at Kudal; 9/57 [15.8%] and 22/94 [23.4%] at Atit; p > 0.1). Excluding IgG anti-HEV positive samples from the analysis also yielded non-significant results. Of the 32 follow-up samples collected from family contacts without IgG or IgM antibodies to HEV in the initial blood sample, 31 remained IgM and IgG anti-HEV negative at the end of 1 month. One of the family contacts was found to be IgG anti-HEV positive in the second blood sample. The disease was not related to the index case.

CONCLUSION

Intrafamilial spread of HEV is negligible.

Retrospective serological analysis of hepatitis E patients: a long-term follow-up study

The aim of this study was to evaluate the persistence and protective role of antibodies to hepatitis E virus (anti-HEV) after natural hepatitis E infection. A retrospective analysis of immunoglobulin G (IgG) anti-HEV was performed in 37 patients followed-up for 5 years after epidemics of HEV. Two patients with sporadic hepatitis E (HE) were followed-up for 12 and 8 years. All patients infected during epidemics of HE were positive for IgG anti-HEV at 5 years of follow-up (geometric mean titre: 174.75). The two patients with sporadic HE were positive for IgG anti-HEV at the end of 12 and 8 years of follow-up (the IgG anti-HEV titre was 1: 200 in each patient). This study showed protection against disease by antibodies to HEV. It was therefore concluded that hepatitis E may be preventable by an efficacious vaccine.

Prevalence of hepatitis a antibodies in western Indian population: changing pattern

This report pertains to a retrospective study conducted between 1983 and 1995 at three time points to evaluate the prevalence of hepatitis A virus (HAV) infection in the population of Bhor Taluk, situated in western India. Serum samples from children and adults were tested for anti-HAV antibodies using blocking ELISA test. There was a significant decrease in anti-HAV prevalence among children aged 5-10 years in 1995 (87.36%) as compared to that of 1983 (97.58%) and 1987 (96.48%). All individuals >11 years of age were seropositive for anti-HAV antibodies. Anti-HAV prevalence was similar in the users of well water, but was significantly reduced in individuals supplied with piped water in 1995 (88.61%) compared with that in 1983 (98.77%). A significant decrease in anti-HAV positivity was noted in children from Bhor Taluk as compared to children from Pune bled in 1992. These results underline the need for periodic surveillance of seroepidemiology of hepatitis A to determine the measures for prevention and control of the disease.

Long-term serological follow up and cross-challenge studies in rhesus monkeys experimentally infected with hepatitis E virus

BACKGROUND/AIMS

The aims of this study were to examine the decline of IgG anti-HEV antibodies over a period of 7 years in rhesus monkeys experimentally infected with hepatitis E virus, and to assess the protectivity of these antibodies by challenging the monkeys with a heterologous isolate of hepatitis E virus, 5 years after the primary inoculation.

METHODS

Nine rhesus monkeys (six non-pregnant and three pregnant at the time of hepatitis E virus inoculation) were followed serologically and biochemically for 7 years post-inoculation. Based on regression analysis, estimated time for IgG anti-HEV titers to reach 1:100 or 1:50 was calculated. Three of the monkeys inoculated initially with AKL-90 isolate and challenged 2 years later with PUN-85 isolate of hepatitis E virus were rechallenged with KOL-91 isolate of the virus, 5 years post-primary inoculation. Evidence of viral replication was assessed by measuring serum alanine aminotransferase levels, excretion of the virus in feces or bile (reverse-transcription polymerase chain reaction) and rise in IgG anti-HEV titers (ELISA).

RESULTS

None of the challenged monkeys showed evidence of disease. In contrast to extensive replication of the virus in anti-HEV-negative control monkeys, limited replication was noted in one of the challenged monkeys. The estimated time for the titers to reach 1:100 or 1:50 varied from 3.15 to 44.9 years (19.4+/-11.6 years) and 6.9 to 84.3 years (35.4+/-21.3 years), respectively. Decline in titers was independent of the pregnancy status at the time of infection or reexposure of the monkeys to HEV CONCLUSION: The results show persistence of IgG anti-HEV antibodies for a long time and protectivity of low titered antibodies against reinfection, leading to disease even after intravenous exposure to a heterologous isolate of hepatitis E virus.

Insignificant prevalence of antibodies to hepatitis C in a rural area of western Maharashtra

OBJECTIVE

To determine the age-specific seroprevalence of hepatitis C virus (HCV) in a rural population in Maharashtra.

METHODS

1054 serum samples collected from apparently healthy persons were tested by recombinant immunoblot assay for antibodies against HCV (anti-HCV). Anti-HCV positive samples were tested for HCV-RNA by nested reverse transcriptase polymerase chain reaction (RT-PCR).

RESULTS

One man tested positive for anti-HCV; his sample was also HCV-RNA positive.

CONCLUSIONS

HCV infection is infrequent in this rural area in Maharashtra.

Exposure of Indian children to hepatitis A virus & vaccination age

It is known that 90 per cent of children in India are exposed to hepatitis A virus (HAV) by the age of six years. The aim of the study was to determine when in early childhood maximum HAV infections take place and to deduce an appropriate age for vaccination against HAV. Blood samples of 499 children between the ages of three days and six years were collected and tested for the presence of antibodies against hepatitis A. A statistically significant negative correlation between IgG anti-HAV and age was observed (P < 0.01) up to 11.67 months when IgG anti-HAV positivity was found to be minimum (9.25%). Subsequently a significant positive correlation was noted (P < 0.01). Exposure to HAV was 28.9 per cent soon after the waning of maternal antibodies in the 13-15 month age group which increased to 52.5 per cent by two years of age and 90.9 per cent by 6 yr. It is concluded that in addition to other preventive measures, if children in India are to be vaccinated against hepatitis A they should be immunised against HAV by 9-10 months of age when the maternal antibodies disappear.

Role of immune serum globulins in pregnant women during an epidemic of hepatitis E

The efficacy of an Indian preparation of immune serum globulins (ISG) was evaluated among pregnant women during an epidemic of hepatitis E in Karad, Western India from January to March 1993. Ten of 55 women receiving ISG developed immunoglobulin M (IgM) antibodies to hepatitis E virus (anti-HEV) during the 1 month of follow-up compared with 18 out of 53 control subjects. Although the total number of recent HEV infections was significantly less in the ISG-treated group, no significant difference could be shown in the proportion of clinical hepatitis E cases because of the very small numbers of patients who developed clinical disease. The observed marginal beneficial effect of ISG might be the result of a low immunoglobulin G (IgG) anti-HEV IgG titre (1:500) of the ISG preparation used. Preparation and testing of high-titred ISG should be a high priority for protecting pregnant women during epidemics of hepatitis E.

Detection of HEV RNA in faeces, by RT-PCR during the epidemics of hepatitis E in India (1976-1995)

Out of the 15 hepatitis E (HEV) epidemics that occurred during the years 1976-1995 in the Gujarat and Maharashtra states of India, 45.78% (76/166) stool samples showed the presence of HEV RNA. HEV RNA was found significantly more often in samples that were transported in liquid nitrogen (50.9%) compared with samples that were transported in wet ice (37.0%) (P < 0.05). Stool samples collected within 7 days after the onset of the disease (59.2%) were more often positive for HEV RNA when compared with samples that were collected 7-20 days after the onset of the disease (28.5%) (P < 0.01). It has been observed in experimentally infected Rhesus monkeys that they excrete HEV throughout the incubation period and for a variable length of time after the elevation of serum ALT levels. A similar situation is found in humans.

Hepatitis A in day care centre

A focal outbreak of hepatitis was detected in a day-care centre for children centrally located in Pune. The source of infection was suspected to be an 11-year-old child who probably got the infection from his school. Seven out of 15 children from day-care centre developed clinical hepatitis. Two cases of secondary infection were identified among the family contacts of infected children. Sera from all the nine sick children were positive for anti-hepatitis A virus-IgM antibodies. A stool sample from a case of secondary infection showed presence of HAV-RNA by RT-nested PCR. These findings proved that the outbreak was caused by hepatitis A virus.

Cross-challenge studies in rhesus monkeys employing different Indian isolates of hepatitis E virus

The aim of this study was to determine if rhesus monkeys infected with one isolate of hepatitis E virus (HEV) were immune to subsequent challenge with other isolates of the virus. Three epidemic and one sporadic Indian HEV isolates were employed in the study. The interval between primary inoculation and challenge varied from 1 year and 6 months to 2 years and 9 months. Evidence of HEV infection was ascertained by rise in serum alanine transaminase (ALT) levels and/or seroconversion to antibodies to HEV (anti-HEV), and the presence of HEV-RNA in the bile or faeces of the infected monkeys. No evidence for multiplication of virus in monkeys challenged with different HEV isolates was obtained. These results show that immunity generated by one isolate of HEV protects against different isolates of hepatitis E virus.

Prevalence of anti-HCV antibodies in western India

Nearly 2000 serum samples collected from different risk groups from Pune and Bombay metropolitan areas were tested for antibodies to hepatitis C virus (anti-HCV) by Recombinant Immunoblot Assay-3 (RIBA-3). Patients undergoing haemodialysis showed 24.5 per cent seropositivity whereas 5.7 and 5.3 per cent of multiply transfused patients (>2 units) and chronic liver disease patients respectively were anti-HCV positive. Leprosy patients had almost 0.7 per cent seropositivity. In other risk groups the positivity rate was nil. In normal population only one out of 830 persons had anti-HCV antibodies. It is therefore apparent that the prevalence of hepatitis C virus (HCV) in western India is not high. However, special care needs to be taken for dialysis patients. As none of the 430 pregnant women and 86 children below the age of 5 yr were anti-HCV positive, vertical mode of HCV transmission seems to be negligible.

Age-specific prevalence of antibodies to hepatitis A and E viruses in Pune, India, 1982 and 1992

The age-specific seroprevalence of antibody to hepatitis A virus (HAV) and antibody to hepatitis E virus (HEV) were studied in persons in Pune, India, where both viruses are endemic. The data showed that HAV infected the majority of persons by age 3 years and virtually 100% by late childhood. In contrast, infection with HEV was rare in children and did not reach peak prevalence (33%-40%) until early adulthood. The reason for the differences in infection rates between HAV and HEV is not known. Age-specific antibody patterns in serum samples obtained 10 years apart show that neither HAV nor HEV has diminished in medical importance in this Indian community.

Seroepidemiology of water-borne hepatitis in India and evidence for a third enterically-transmitted hepatitis agent

Many epidemics of water-borne hepatitis have occurred throughout India. These were thought to be epidemics of hepatitis A until 1980, when evidence for an enterically transmitted non-A, non-B hepatitis was first reported. Subsequently, hepatitis E virus was discovered and most recent epidemics of enterically transmitted non-A, non-B hepatitis have been attributed to hepatitis E virus infection. However, only a limited number of cases have been confirmed by immuno electron microscopy, polymerase chain reaction, or seroconversion. In the present study we have performed a retrospective seroepidemiologic study of 17 epidemics of water-borne hepatitis in India. We have confirmed that 16 of the 17 epidemics were caused at least in part by serologically closely related hepatitis E viruses. However, one epidemic, in the Andaman Islands, and possibly a significant minority of cases in other epidemics, appears to have been caused by a previously unrecognized hepatitis agent.

Rhesus monkeys infected with hepatitis E virus (HEV) from the former USSR are immune to subsequent challenge with an Indian strain of HEV

Two rhesus monkeys (M. mullata) of approximately two years of age were inoculated intravenously with a 10% suspension of hepatitis E virus (HEV) positive stool from Kirghistan as evidenced by immuno-electron microscopy. Evidence of HEV infection was demonstrated by rise in serum alanine transaminase (ALT) levels and seroconversion of these monkeys to anti-HEV after 1-1/2 months post-inoculation as evidenced by immunoblot. One year after the primary inoculation, these monkeys were challenged with an Indian strain of HEV. No rise in serum ALT levels was noted during an observation period of 6 months. The same inoculum produced HE in two rhesus monkeys. The results showed that strains from India and Kirghistan were antigenically closely related and rhesus monkeys infected with one strain of virus were immune to another strain.

Synthesis of racemic 6,10,14-trimethylpentadecan-2-ol, a pheromone of rice moth and 5,9,13-trimethyltetradecanoic acid, a component of marine sponge from a common intermediate

A facile synthesis of dl-6,10,14-trimethylpentadecan-2-ol (1) a pheromone component of rice moth, Corcyra cephalonica Stainton and 5,9,13-trimethyltetradecanoic acid (2) a component of marine sponge, Cinachyrella alloclada Uliczka, using a common, intermediate, hexahydrofarnesol is accomplished. The salient features for 1 are: Grignard coupling of 5 with allylmagnesium bromide and oxymercuration-demercuration whereas for 2 they are: Knoevenagel condensation and subsequent hydrogenation.

Aetiology of acute sporadic non-A, non-B viral hepatitis in India

Non-A, non-B (NANB) hepatitis viruses are now classified as hepatitis E (enterically transmitted) and hepatitis C (parenterally transmitted). India experiences a large number of epidemics of the enteric disease every year. In addition, about 70% of the sporadic cases among adults are also due to NANB hepatitis. With the availability of an immunoblot assay for the detection of anti-HEV-IgM and the polymerase chain reaction (PCR) for the detection of HCV-RNA, serum samples from epidemic and sporadic NANB patients were screened for these markers. We found that a large number of cases from the epidemics were HEV, though a few remained undiagnosed, while of the sporadic cases only a few could be diagnosed as HCV or HEV; a large proportion remained undiagnosed.

Hepatitis E virus infection in pregnant rhesus monkeys

Ten non-pregnant female monkeys and four pregnant monkeys (all Macaca mulatta) in the last third of their gestation period were infected intravenously with the stool sample of a patient with hepatitis E virus infection (immuno-electronmicroscopy positive for hepatitis E virus). Four more non-pregnant monkeys were inoculated with a lower dose (less number of virus particles by IEM) of a stool sample collected on a different day from the same patient. The average incubation period as evidenced by the rise of serum alanine transferase in the non-pregnant monkeys, was 36.4 +/- 4.9 days. The dose of the virus did not affect the incubation period. Two of the pregnant monkeys had incubation periods of 9 and 13 days respectively. They delivered healthy babies on 40th and 53rd day respectively after inoculation. At the age of 11 months, both babies were negative for anti-HEV antibodies. One monkey which delivered a healthy baby on the 2nd day after inoculation had incubation period of 36 days. The baby of this monkey was anti-HEV positive at the age of 11 months. The incubation period was 41 days in the fourth monkey which delivered a macerated foetus on the 36th day after infection. No fatality was recorded in the infected monkeys. Bile samples collected from all monkeys showed strong signals in nested polymerase chain reaction (PCR). It seems that the incubation period in pregnant monkeys was determined by the state of pregnancy.