Infectious hepatitis (hepatitis A) research in nonhuman primates.

A satisfactory animal model has been found for laboratory studies of human hepatitis A-namely, the white-moustached marmoset (Saguinus mystax). With this species it has been possible to perform serum-neutralization tests and to develop immune-adherence and complement-fixation tests demonstrating antigen and antibody to the virus. The recent work in marmosets has also led to determination of the agent's characteristics: it most closely resembles the enteroviruses of the picornavirus family. These advances open the way for development of a routine serologic test for diagnosis of the disease, of a human immune globulin for general use that would be precisely standardized for hepatitis A antibody, and, ultimately, of a vaccine. They also provide bases for epidemiologic studies that could reveal nonspecific measures for the disease's control. In addition, there is indication that marmosets could be used for safety control of the hepatitis B vaccine that has already been developed. An adequate supply of S. mystax-threatened by recent embargoes on their exportation-is essential to continuation of this work. The question of marmoset supply, both in the short term and over the long range, deserves serious review.

Seroepidemiologic investigations of human hepatitis caused by A, B, and a possible third virus.

Seroepidemiologic studies were made of normal subjects in populations in the United States and Costa Rica and in family outbreaks of hepatitis in Costa Rica. Hepatitis A affected a majority of children of very young age in Costa Rica, while such experience in persons of high socioeconomic status in the United States did not occur before middle life. Persons of low socioeconomic status (paid plasma donors) and residents and attendants of institutions for the mentally retarded showed a far greater incidence of hepatitis A antibody than did their counterparts in the open community. Hepatitis A and B epidemics occurred in families in Costa Rica with rapid spread to other susceptible members of the group. The disease was clinically apparent in roughly half the cases, whether the responsible agent be hepatitis A or B. Five cases of nonhepatitis A or B (hypothetical hepatitis C) were found and all but one of them were subclinical.

Development and utilization of complement-fixation and immune adherence tests for human hepatitis A virus and antibody.

The reliable propagation of CR326 strain of human hepatitis A virus in Saguinus mystax marmosets has permitted the development of specific serum neutralization, complement-fixation (CF), and immune adherence (IA) assays for hepatitis A antigen and antibody. The CF and IA assay were made possible by the use of livers of CR326-infected marmosets as a source of hepatitis A antigen. All assays were shown to be specific for hepatitis A. Patients with hepatitis B did not show development of hepatitis A antibody. Hepatitis A antibody appeared following onset of illness, and, in the longest time period studied, has persisted for seven years. Epidemiologic studies have been performed on several Costa Rican families with outbreaks of hepatitis, with the IA and CF assays. Also, several populations in the U.S.A. were studied. These indicated a high incidence of hepatitis A at an early age in Costa Rica and a relatively low incidence of hepatitis A antibody among adults in the U.S.A. It was shown that human immune globulin can be standardized for hepatitis A antibody content by the IA assay. Finally, the IA assay indicated probable hepatitis A antibody in uninoculated chimpanzees, grivet monkeys, and rhesus monkeys.

Biophysical and biochemical properties of CR326 human hepatitis A virus.

CR326 human hepatitis A virus purified by isopycnic banding from infected marmoset sera was shown to consist of 27 mmu spherical particles on electron microscopic examination. The particles were identified as hepatitis A virus by tests by infectivity and by specific neutralization of infectivity with convalescent human hepatitis A serum. Also, identical 27 mmu viruses in liver extracts gave specific reactions with hepatitis A antisera when tested by immune electron microscopy. The buoyant density of the virus in CsCl was 1.34 and it was heat (60 C), ether, and acid stable but was destroyed by heat (100 C), formalin (1:4000), and ultraviolet irradiation. Electron microscopic studies of sections of infected marmoset liver showed intracytoplasmic virus particles, usually in vesicles. Presumptive findings for RNA, together with the intracytoplasmic location of the virus, indicated the virus to be of RNA-type. The attributes of the virus indicate it is closely related to the enterovirus family and not to hepatitis B virus.

Specific immune adherence assay for human hepatitis A antibody application to diagnostic and epidemiologic investigations.

A specific immune adherence (IA) test for hepatitis A antibody in human serum was described employing liver extract of marmosets infected with CR326 strain human hepatitis A virus. Persons with hepatitis A, but not hepatitis B, developed hepatitis A IA antibody soon after onset of the acute illness and this persisted thereafter. There was very close agreement in the tests for human hepatitis A immune adherence, complement fixing (CF) and neutralizing antibodies. IA antibodies appeared to develop somewhat later than CF or neutralizing antibody. A limited epidemiologic study of a family outbreak of hepatitis A and B in Costa Rica showed simultaneous occurrence of the two diseases and was supportive of the concept that susceptible persons in a country with high hepatitis A prevalence generally acquire their infections at an early age and are immune thereafter. Most persons of high socioeconomic level in an area of low hepatitis A incidence may proceed to adulthood without experience with hepatitis A. Person of low socioeconomic level, however, such as commercial blood bank donors and prisoners, show high incidence of hepatitis A antibody. Hepatitis IA and CF antibodies persisted in human subjects for at least 7 hr after hepatitis A virus infection. Captive chimpanzees and grivet and rhesus monkeys, not given hepatitis A virus, showed evidence of previous experience with human hepatitis A or an antigenically related virus based on tests for hepatitis A antibody. Other subhuman primates, rodents, and swine, not given hepatitis A virus, were without hepatitis A antibody. The IA test provides an excellent tool for diagnostic and epidemiologic investigations of hepatitis A and should be of considerable value to detect hepatitis A virus in attempts to propagate the virus in cell culture. There was considerable difference in hepatitis A IA antibody content of different lots of commercial human immune globulin, though the majority titered 1:4000 or 1:8000.

A specific complement-fixation test for human hepatitis a employing CR326 virus antigen. Diagnosis and epidemiology.

A specific diagnostic complement-fixation test for hepatitis A antibody in human serum was described employing livers of marmosets infected with CR326 strain human hepatitis A virus. Persons with hepatitis A, but not hepatitis B, developed hepatitis A CF antibody shortly after the onset of illness and this persisted thereafter. Good agreement was noted in the development of CF and neutralizing antibodies in hepatitis A cases. Hepatitis A was shown to occur in a person with hepatitis B antigenemia and hepatitis B occurred in persons with hepatitis A antibody. Most persons with hepatitis A who were tested, but none of those with hepatitis B, developed increased anticomplementary activity in their sera at the time of onset of illness. At least one patient with hepatitis A developed antibody against normal liver that persisted. The possible inplications of this in relation to pathogenesis and to non-specific diagnostic tests in hepatitis were discussed. A limited epidemiologic study of a family outbreak of hepatitis in Costa Rica and of a group of young adults in our epidemic country acquire their infections at an early age and are immune thereafter; persons in areas of relatively low incidence may proceed into adulthood without experience with hepatitis A. The CF test should provide an excellent tool for diagnosis and for epidemiologic investigation of hepatitis A and should be of considerable value to detect hepatitis A virus in attempts to propagate the virus in cell culture.

Physical, chemical and morphologic dimensions of human hepatitis A virus strain CR326 (38578).

CR326 human hepatitis A virus purified by isopycnic banding from infected marmoset sera was shown to consist of 27 nm spherical particles on electron microscopic examination. The particles were identified as hepatitis A virus by tests for infectivity and by specific neutralization of infectivity with convalescent human hepatitis A serum. Also, indentical 27 nm viruses in liver extracts gave specific reactions with hepatitis A antisera when tested by immune electron microscopy. The bouyant density of the virus in CsCl was 1.34 and it was heat (60 degrees), ether and acid stable but was destroyed by heat (100 degrees), formalin (1:4000) and ultraviolet irradiation. Electron microscopic studies of sections of infected marmoset liver showed intracytoplasmic virus particles, usually in vesicles. Presumptive findings for RNA, together with the intracytoplasmic location of the virus, indicated the virus to be of RNA-type. The attributes of the virus indicate it is closely related to the enterovirus family and not to hepatitis B virus.

Immune adherence and complement-fixation tests for human hepatitis A. Diagnostic and epidemiologic investigations.

The reliable propagation of CR326 strain of human hepatitis A virus in Saguinus mystax marmosets has permitted the development of specific serum neutralization, complement-fixation (CF), and immune adherence (IA) assays for hepatitis A antigen and antibody. The CF and IA assays were made possible by the use of livers of CR326-infected marmosets as a source of hepatitis A antigen. All assays were shown to be specific for hepatitis A. Cases of hepatitis B did not show development of hepatitis A antibody. Hepatitis A antibody appeared following onset of illness, and, in the longest time period studied, has persisted for 7 years. Epidemiologic studies have been performed on several Costa Rican families with outbreaks of hepatitis, using the IA and CF assays. Also, several populations in the U.S.A. were studied. These indicated a high incidence of hepatitis A at an early age in Costa Rica and a relatively low incidence of hepatitis A antibody among adults in the U.S.A. It was shown that human immune globulin can be standardized for hepatitis A antibody content by the IA assay. Finally, the IA assay indicated probable hepatitis A antibody in uninoculated chimpanzees, grivet monkeys, and rhesus monkeys.

Characterization of CR326 human hepatitis A virus, a probable enterovirus.

CR326 human hepatitis A virus purified by isopycnic banding from infected marmoset sera was shown to consist of 27 mmu spherical particles on electron microscopic examination. The particles were identified as hepatitis A virus by tests for infectivity and by specific neutralization of infectivity with convalescent human hepatitis A serum. Also, identical 27 mmu viruses in liver extracts gave specific reactions with hepatitis A antisera when tested by immune electron microscopy. The buoyant density of the virus in CsCl was 1.34 and it was heat (60 degrees C), ether and acid stable but was destroyed by heat (100 degrees C), formalin (1:4000) and ultraviolet irradiation. Electron microscopic studies of sections of infected marmoset liver showed intracytoplasmic virus particles, usually in vesicles. Presumptive findings for RNA, together with the intracytoplasmic location of the virus, indicated the virus to be of RNA-type. The attributes of the virus indicate it is closely related to the enterovirus family and not to hepatitis B virus.