[Propagation of hepatitis E virus in an endemic and nonendemic regions]. / Osobennosti rasprostraneniia virusa gepatita E v éndemichnom i neéndemichnom regionakh.

The role of hepatitis E (HE) in sporadic morbidity at an endemic territory (Southern Uzbekistan) and the incidence of anti-HEV in different populations of a nonendemic region (Russia) were evaluated. Antibodies to HEV were detected in 22.1% of patients with acute HE, including mixed infections (+ HA or HB), in the Dekhkanabad district of Kashkadarya region in 1993. The estimated incidence of acute HE was 51.7 per 100,000 population. Analysis of monthly incidence of acute HE demonstrated a seasonal pattern of the morbidity: more than 80% of total recorded cases occurred in August-September. These data indicate the presence of group HEV infections and an important role of this infection in the structure of acute viral hepatitis at the endemic territory. Anti-HEV were found in some population groups at a nonendemic territory: in free-of-charge blood donors in Surgut (4%), in patients with HIV infection (1.6%), and in medical workers in Moscow (1.1%).

[Study of hepatitis E virus replication in FRhK-4 cell culture]. / Izuchenie replikatsii virusa gepatita E v kul'ture kletok FRhK-4.

The cytolytic form of hepatitis E virus reproduction in FRhk-4 cells is described. The cytopathic effect was observed by days 6-7 of the 25th passage in this cell culture. Reverse transcription with polymerase chain reaction were used to study virus reproduction daily for 10 days postinfection. The virus replication starts on day 4 after inoculation. The development of the cytopathic effect depended on the serum concentration in culture medium, whereas the virus replication did not depend on this factor. The replicative form (-RNA) of viral RNA appeared on day 4 postinoculation, as did the new genomic one (+RNA).

[Hepatitis E in a nonendemic region: antibodies to hepatitis E virus in various groups of residents]. / Gepatit E v neéndemichnom raine: antitela k virusu gepatita E v razlichnykh gruppakh naseleniia.

Increase in the number of seropositive subjects in the population of European and North-American regions not endemic for hepatitis E stimulated research in this field. This study was aimed at investigating the incidence of IgG antibodies to hepatitis E virus (anti-HEV-IgG) in subjects with different liver diseases and in groups at increased risk of infection in a nonendemic region. In patients with different diseases of the liver the incidence of anti-HEV-IgG varied from 5.1 to 14.3%, in medical workers and former blood donors not allowed to donate blood because of increased transaminase levels in the blood 5.1 and 5.3%, respectively. In the reference group this level was appreciably lower-only 1.8%, this being rather close to the incidence of anti-HEV-IgG in the population of a nonendemic region (2.1%). There were no seropositive women in the group of healthy pregnant women in a non-endemic region, whereas in an endemic region (in Kyrghyzstan) 15% of pregnant women were seropositive for anti-HEV.

[Further study of experimental hepatitis E in piglets]. / Dal'neishee izuchenie éksperimental'nogo gepatita E u porosiat.

Experimental infection of piglets with a fecal pool containing hepatitis E virus (HEV) strains Osh-25 and Osh-228 confirmed previous results obtained with HEV strain Osh-205 on susceptibility of these animals to hepatitis E. A biphasic increase of transaminase activities, histopathologic changes in the liver, virus excretion with feces were observed in the animals. The genome of viral particles in piglet feces conformed, at least partially, to human HEV RNA. Ultrastructural abnormalities of piglet hepatocytes resembled those in primates with experimental hepatitis E. The number of positive results (during follow-up of the particles and HEV RNA in various organs of experimental animals) was the highest on day 10 after infection. Both the particles and HEV RNA were present in the lymphoid tissue over the entire follow-up period, from day 5 to day 15 postinfection.

[An experimental infection in lambs by the hepatitis E virus]. / Eksperimental'naia infektsiia iagniat virusom gepatita E.

Lambs were experimentally infected with a pool of 10% hepatitis E (HE) patient fecal suspension containing HE virus (HEV) isolates Osh-225 and Osh-228 which caused an infection closely resembling experimental HE in primates. Clinical manifestations consisted of acute biochemical and histological hepatitis, virus shedding in feces, the presence of virus-like particles in the peripharyngeal lymph nodes and the contents of small intestine, of HEV RNA in the parenchymal organs of lambs. Susceptibility of lambs to HEV derived from the infected piglets and the possibility of passaging the piglets' HEV in lambs was demonstrated. This passaging led to shortening of the incubation period.

[The possible involvement of rodents in the spread of viral hepatitis E]. / Vozmozhnoe vovlechenie gryzunov v rasprostranenie virusnogo gepatita E.

The outbreak of hepatitis E among humans in July-October 1989 in the village of Dzhigdele (140 km to the northeast of Osh) is described. During this outbreak 23 rodents of different species (4 Turkestan rats, 15 house mice and 4 wood mice) were caught within a radial distance of 1 km from the village. 5 out of these 23 animals were found to have hepatitis E virus, detected by the method of immuno-electron microscopy, in their blood sera. Under experimental conditions 7 noninbred white mice were inoculated with material obtained from a previously infected Javanese macaque and a hepatitis E patient. The use of immunoelectron microscopy made it possible to reveal the excretion of the virus with feces on days 4 to 19-23 after inoculation and the development of specific seroconversion in all 7 infected animals. On the basis of these data a suggestion was made that rodents probably played a certain role in the process of the spread of viral hepatitis E.

[The biochemical indices of the blood serum in experimental hepatitis A in tamarins]. / Biokhimicheskie pokazateli syvorotki krovi pri éksperiemental'nom gepatite A u tamarinov.

Serum biochemical parameters were studied in 42 healthy wild-caught adult tamarins (S. mystax), males and females, to determine the normal values. Blood samples were drawn repeatedly, and the serum was tested for aspartate aminotransferase, alanine aminotransferase, isocitric dehydrogenase, serum glucose, serum urea, triglyceride, cholesterol, albumin, and total protein. The results indicated that serum chemistry values were similar to those reported as normal for both humans and other Callitrichidae species. The study of serum biochemical parameters in tamarins with experimental hepatitis A indicated that serum enzyme activities alone reflected the hepatic damage, while other biochemical parameters were of no real clinical importance. The experimental results showed the levels of serum urea to be indicative of the pathological involvement of the kidneys in experimental hepatitis A in some cases.

[Synthesis and immunochemical properties of oligopeptides--fragments of capsid proteins of the hepatitis A virus]. / Sintez i immunokhimicheskie svoistva oligopeptidov--fragmentov kapsidnykh belkov virusa gepatita A.

The hepatitis A virus (HAV) capsid protein VP1, VP2 and VP3 are exposed at the virion surface and should therefore contain antigenic determinants. Algorithms for hydrophilicity, antigenicity and flexibility were used to predict probable antigenic sites. Synthesis of 7- to 23-membered overlapping peptides from seven sites, viz., 1-11, 1-17, 2-33, 11-25, 73-82, 76-86, 98-109, 98-112, 102-107, 102-108, 108-127, 113-123, 118-140, 276-298 from VP1, 42-62 from VP2, 76-85 from VP3, and 1-23 from VP4, was performed by various solid-phase methods. Free peptides and their conjugates with different carriers were used for immunization and study of antigenicity. The peptides did not interact with antibodies to the hepatitis A virus, whereas their conjugates did not induce the formation of anti-HAV-antibodies.

[Experimental hepatitis E infection in piglets]. / Eksperimental'naia infektsiia gepatita E u porosiat.

A sample of patient's faeces containing virus-like particles (VLP) of 27-34 nm was obtained during an outbreak of hepatitis E in the Kirghiz SSR. The identity of the VLP to hepatitis E virus and etiological association with the disease were demonstrated by immune electron microscopy and infection of Macaca fascicularis monkeys. This isolate of hepatitis E virus is able to induce experimental infection in domestic piglets which was very similar to experimental hepatitis E in primates when infected orally, intravenously and by the combined routes. The clinical manifestations included acute biochemical and histological hepatitis, excretion of hepatitis E virus in faeces, icteric sclerae and skin, hepatitis virus presence in the material from mesenteric lymph nodes. Immunosuppression aggravated hepatitis E infection in piglets. Piglet-to-piglet transmission of hepatitis E virus was demonstrated. During passages of the virus in piglets a shortening of the incubation period and the absence of jaundice was observed.

[A comparative study of the sensitivity and specific activity of an immunoenzyme test system for determining class-M antibodies to the hepatitis A virus]. / Sravnitel'noe izuchenie chuvstvitel'nosti i spetsificheskoi aktivnosti immunofermentnoi test-sistemy dlia opredeleniia antitel klassa M k virusu gepatita A.

The diagnostic value of the first experimental production batches of assay kit "DIAGN-A-HEP", produced at the Institute of Poliomyelitis and Viral Encephalitides (USSR Acad. Med. Sci.) and intended for the determination of IgM to hepatitis A virus (HAV) in the enzyme immunoassay (EIA), has been studied in comparison with that of the internationally known and widely approved commercial EIA system "HAVAB-MEIA" for the determination of antibodies to HAV (the product of Abbott, USA). The study has revealed that the EIA kit "DIAGN-A-HEP" is highly sensitive and specific, and the diagnostic value of this kit is not inferior to that of the commercial assay system "HAVAB-MEIA". On the basis of this study the use of the EIA kits "DIAGN-A-HEP" in medical practice has been allowed by the decree of the Ministry of Health of the USSR.

[The antigenic properties of hepatitis A virus particles possessing different physicochemical characteristics]. / Antigennye svoistva chastits virusa gepatita A, obladaiushchikh razlichnymi fiziko-khimicheskimi kharakteristikami.

A modified enzyme immunoassay based on adsorption of antihepatitis A virus (HAV) IgG-HRPO conjugate and monoclonal antibodies to HAV were used to investigate antigenic differences between mature HAV virions and subviral particles with different buoyant densities in CsCl produced in HAV-infected cells. The mature virions (1.34 g/cm3) appeared to have common antigenic determinants with subviral particles (1.20, 1.27, and 1.30 g/cm3) and possess some additional determinants. Nevertheless, both subviral particles and mature virions induced antibodies capable of neutralizing HAV infectivity in tissue culture.

[The synthetic peptide 62-75 VP3 of the hepatitis A virus induces virus-binding antibodies]. / Sinteticheskii peptid 62-75 VP3 virusa gepatitia A indutsiruet virussviazyvaiushchie antitela.

Peptide (P6) representing amino acids 62-75 of HAV capsid protein VP3 was synthesized. Pure P6, octamer form of P6, and P6 conjugated to KLH were injected into rabbits. The sera against these preparations reacted with denaturized VP3 in immunoblotting tests; however, only anti-P6-KLH serum was capable of binding the native HAV.

[Mapping of the structural proteins of the hepatitis A virus]. / Kartirovanie strukturnykh belkov virusa gepatita A.

The Western blot procedure with highly specific antipeptide antibody was applied to identify the electrophoretic mobility of hepatitis A virus capsid proteins. Polypeptides with molecular weights of 33, 29 and 27 kDa proved to be VP1, VP2, and VP3 proteins as they reacted with sera generated to VP1 recombinant protein and to synthetic oligopeptides 42-62 VP2 and 62-75 VP3, respectively.

[The development of the epidemic process and the formation of humoral immunity to the hepatitis A virus in adolescent collectives]. / Razvitie épidemicheskogo protsessa i formirovanie gumoral'nogo immuniteta k virusu gepatita A v podrostkovykh kollektivakh.

Additional observation on the formation of humoral immunity to hepatitis A virus has been carried out in 2,375 adolescents aged 15-17 years and belonging to 12 groups at 3 areas of the USSR. This observation has shown that in the presence of a high level of the immune stratum the spread of infection occurs, as a rule, outside the group under observation. Besides, as revealed in this study, the risk of seroconversion and the loss of specific antibodies are, respectively, directly and inversely related to the level of the immune stratum in the group. The level of the immune stratum in a given age group supposedly reflects the intensity of the development of the epidemic process at a definite area.

[The modelling of hepatitis A and of enterally transmitted non-A, non-B hepatitis (hepatitis E) in Saguinus mystax tamarins]. / Modelirovanie gepatita A i énteral'no peredaiushchegosia gepatita ni A, ni B (gepatita E) na tamarinakh Saguinus mystax.

A comparative study of hepatitis infection caused by human hepatitis A virus (MS-1 strain), simian hepatitis A virus (AGM-27 strain), and enterically transmitted non-A, non-B hepatitis virus (Tashkent-1435 strain) was carried out. Susceptibility of tamarins to the AGM-27 and Tashkent-1435 as well as to MS-1 strain was demonstrated. All the strains induced an acute infection characterized by serum alanine aminotransferase (ALT) elevation, virus excretion and antibody response. Certain differences in the course of infection caused by these strains were observed in the duration of the incubation period and ALT profiles.

[A trial of a cultured inactivated vaccine against hepatitis A on Saguinus mystax tamarins]. / Ispytanie na tamarinakh Saguinus mystax kul'tural'noi inaktivirovannoi vaktsiny protiv gepatita A.

An experimental batch of inactivated hepatitis A vaccine was prepared using hepatitis A virus (HAV), HAS-15 strain, adapted to cell culture and purified by ultracentrifugation. The vaccine was tested in tamarins immunized intramuscularly three times one month apart. Three tamarins received a vaccine preparation containing 10 ng of immunogen each, three--100 ng each, and three animals were used as controls. The efficacy was judged by the anti-HAV antibody response in the vaccinated animals and development of immunity to subsequent virus challenge two months after the last immunization. The criteria of infection were: elevation of serum alanine aminotransferase, fecal excretion of HAV and production of specific antibody of IgM class. The immune response to 10 ng of the immunogen was lower than to 100 ng, however, both doses produced complete resistance to infection. The booster effect was observed in animals receiving 10 ng of the immunogen. The vaccine batch under study in the indicated doses was shown to have a good immunogenic potency and protective activity for tamarins.

[Development of an infection in monkeys as a result of their sequential natural and experimental exposure to the hepatitis A virus]. / Razvitie infektsii u obez'ian v rezul'tate posledovatel'nogo estestvennogo i éksperimental'nogo zarazheniia ikh virusom gepatita A.

The development of spontaneous outbreak of hepatitis A (HA) among African green monkeys kept under strict isolation conditions was studied. It was shown that in the case of introduction of HAV the infection involved all the susceptible monkeys, running a course with and without any increase in the level of activity of serum alanine aminotransferase (ALT) After inoculation of commercial gamma-globulin only the infection without the ALT activity increase developed and some monkeys had no signs of HA at all. Experimental reinfection with HAV was produced in monkeys having anti-HAV titres of less than or equal to 1:3500.

[Susceptibility of Macaca rhesus to infection with hepatitis A virus strains isolated from man and monkeys]. / Vospriimchivost' makak rezusov k zarazheniiu shtammami virusa gepatita A, vydelennymi ot cheloveka i obez'iany.

The results of infection of Macaca rhesus monkeys with hepatitis A virus (HAV) strains isolated from monkeys and man are presented. After inoculation of monkeys with human NAV strains the infection could not be reproduced whereas simian HAV strains were found to be pathogenic for M. rhesus monkeys both on experimental inoculation and during natural contacts with infected monkeys in the animal house.