Control of hepatitis B in the Western Pacific region.
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Biomedical subjects
Publications and source records attributed to I D Gust.
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Forty-one strains of adenovirus type 19/37 (Ad19/37) mainly isolated from patients with keratoconjunctivitis or conjunctivitis between 1974 and 1984 were re-evaluated by serum neutralization (SN), haemagglutination inhibition (HI) and DNA restriction analysis. Of 19 isolates which were neutralized to high titre by antiserum prepared against prototype Ad19, 5 showed cross-reactivity with 32-64 units of Ad37 antiserum, while of 22 strains neutralized by high titre by Ad37 antiserum, 3 showed cross-reactivity with 32 units of Ad19 antiserum. By DNA restriction analysis, all Ad19 isolates were identical to each other and to Ad19A virus. Using endonuclease Bgl 1, three variants were observed among the Ad37 isolates.
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Hepatitis A virus (HAV) strain HM-175 was passaged six times in marmosets, 59 times in cell culture and purified from infected cell culture supernatant fluid. The viral RNA was extracted, copied into cDNA and the cDNA:RNA hybrids were cloned into the PstI site of plasmid pBR322. The cDNA clones were authenticated by hybridization to RNA extracted from HAV-infected cells and clones representing the 3' end of the genome were identified using a previously authenticated cDNA clone. The clones represented all but 29 bases of the HAV genome. They were compared to HAV strain HM-175 cDNA cloned from viral RNA after three passages in marmosets on the basis of restriction endonuclease mapping and DNA sequencing. No differences were found in either the presence or absence of restriction endonuclease sites using 33 different restriction enzymes. Sequencing of cDNA representing bases 29 to 1002 of the HAV genome revealed eight base changes all of which were within the 5' noncoding region.
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Serum antibodies to Ross River virus and Murray Valley encephalitis virus were measured during 1974-1975 in residents of Echuca, an urban Murray Valley community. A representative group of volunteers was obtained by random selection of households. The prevalence of antibodies to both viruses increased progressively with age. Prevalence was equal in both sexes for both viruses in all age groups, indicating that the risk of infection was mainly determined by geography rather than by personal activities. Antibody levels remained unchanged in the following year when there was no disease activity in the area. The stability of antibody levels permitted retrospective estimates of mean rates of infection. These were approximately 0.4% per annum for both viruses when age was used as the index for years of exposure. With allowance for other factors, the best estimate for both virus infections is probably closer to 1%. The morbidity rate for Ross River virus infection appeared to be low. It is concluded that infection with Ross River virus and with Murray Valley encephalitis-related viruses is endemic in the Murray Valley.
Hepatitis A virus-specific BSC-1 cells were used for the detection of serum immunoglobulins to hepatitis A virus by indirect immunofluorescence. Of 150 serum samples tested, specific immunoglobulin M was detected only in patients with serologically confirmed acute hepatitis A, while specific immunoglobulin G was detected in patients with acute or past clinical hepatitis A as well as many patients with no known history of hepatitis.
Sufficient data have accumulated to permit the ICTV Study Group on the Nomenclature of Hepatitis Viruses to recognize human hepatitis B virus as a member of a unique group of viruses and to classify it, together with a number of related animal viruses, into a new family called the Hepadnaviridae. Over the past decade, the International Committee on Taxonomy of Viruses (ICTV) has been active in the development of a classification system for viruses. The majority of viruses infecting vertebrate hosts have been classified into families and genera on the recommendations of the Vertebrate Virus Subcommittee (VVSC). In June 1980, the VVSC authorized the formation of an ad hoc Study Group on the Nomenclature of Hepatitis Viruses under the Chairmanship of Dr. Ian D. Gust. This paper represents the first report of the Study Group on the Taxonomic Classification of Human Hepatitis B Virus.
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Icteric patients with clinical and biochemical evidence of liver disease, admitted into various hospitals in Malaysia, were investigated to determine the cause of their infection. Of these patients, 11.0% (16/145) were found positive for IgM anti-HAV (EIA), 4.1% (6/145) for IgM anti-HBc (EIA), 1.0% (1/102) for IgM anti-CMV (ELISA), 17.2% (16/64) for rising titres of leptospiral agglutinin, and none for heterophile antibody of EBV. Hepatitis NANB accounted for 67.9% of cases. The mean serum transaminases (ALT and AST) values in patients with hepatitis A and B were higher (more than 500IU) than in patients with leptospirosis or non-A, non-B hepatitis, whereas serum bilirubin levels were higher in patients with hepatitis A and leptospirosis than in patients with hepatitis B.
A prospective study on 100 homosexual male volunteers was designed to examine immunological function in relation to sexual activity and infection with the human T cell lymphotropic virus Type III (HTLV-III). Complete data were available for 71 men. In a comparison with 100 age-matched heterosexual men, the study group of 100 men had a significantly higher mean serum IgG level (12.1 +/- SD 2.7 g/l vs. 10.9 +/- 2.4 g/l, p less than 0.01) and a significantly lower mean number of CD4 (T4) cells (845 +/- 310 X 10(-6)/l vs. 1128 +/- 375; p less than 0.01). For the study group, seropositivity for anti-HTLV-III was present initially in 22 per cent and was associated with a higher mean level of serum IgG and lower mean number of CD4 cells. Among seropositive homosexual men a low CD4/8 ratio was attributable to low numbers of CD4 cells in those without lymphadenopathy and to high numbers of CD8 cells in those with lymphadenopathy. For the seronegative homosexual men, a low CD4/8 ratio as a result of an increased CD8 cell count was present in 12 of 60, and was associated with numerous sexual partners and semen culture positive for cytomegalovirus. In two seropositive subjects a low CD4/8 ratio due to a decrease in the CD4 cell count was predictive of the development of AIDS by some two years. For the 71 men with complete data over two years, indices of cell-mediated immunity, including mean counts of CD4 cells, the CD4/8 ratio, and score for recall of cutaneous delayed type hypersensitivity increased during the first year but not during the second year in both seropositive and seronegative subjects. These increases occurred in association with changes in sexual practices and activity, but could not be attributed to any one particular factor.
In a group of 126 Australian patients with haemophilia, who were receiving lyophilized clotting-factor concentrates prepared from locally collected plasma, a high prevalence of antibody to human T-cell lymphotropic virus III (HTLV-III) was demonstrated in those with severe disease. Patients with moderate or mild disease had a much lower prevalence of HTLV-III antibody. After heat treatment of lyophilized factor VIII and factor IX concentrates (60 degrees C for 72 hours) to inactivate the virus, the losses of activity of an intermediate-purity and of a fibrinogen-poor factor VIII concentrate, and of the coagulant activity of a factor IX concentrate, were within acceptable limits. The solubility of the intermediate-purity factor VIII concentrate was markedly decreased; the fibrinogen-poor factor VIII concentrate and the factor IX concentrate were readily soluble. In-vivo recovery and survival of heated concentrates were equivalent to those of the unheated products, and they were effective in the treatment of spontaneous and traumatic haemorrhages.
Hepatitis B infection is hyperendemic in the adult population of Niue. In order to determine the age at which infection is acquired and the contribution of vertical and horizontal transmission, the sera from 1055 children were tested for markers of hepatitis B infection. Eleven percent (11.0%) were found to be carriers of hepatitis B surface antigen (HBsAg) and a further 33.6% had antibody to hepatitis B surface antigen (anti-HBs). While less than 15% of the population were infected before the age of two years, these children had the greatest risk of becoming chronic carriers. The simplest method of controlling hepatitis B infection in Niue would be to immunise all newborn babies.
During November and December 1982, a persistent outbreak of gastroenteritis took place in an isolated guest house. An estimated 26% of the changing population of guests and staff developed symptoms. Laboratory studies implicated Norwalk agent as the cause of illness, although the original source of the outbreak could not be established. Information on clinical features of the illness, its mode of spread, and eventual control is presented.
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Rotaviruses were detected by electron microscopy in the faecal specimens of six clinically well cats and virus was subsequently isolated from four of them. Analysis of the RNA of the isolates showed the existence of three electrophoretic types characteristic of the 'long' RNA electrophoretic pattern exhibited by rotaviruses. All feline isolates were neutralized only by antiserum to SA11 rotavirus, indicating that these isolates were serotype 3 rotaviruses. Antiserum prepared against a feline strain neutralized all the feline isolates as well as SA11 but showed no neutralizing activity against human isolates of serotype 1, 2 or 4.
Monoclonal antibodies (K3-2F2 and K3-4C8) raised against hepatitis A virus were used to develop a solid-phase radioimmunoassay and enzyme-linked immunosorbent assay for the detection of hepatitis A virus and antibody. Assays with this pair of monoclonal antibodies were compared in parallel with similarly constructed solid-phase radioimmunoassays and enzyme-linked immunosorbent assays in which human polyclonal serum was used. The monoclonal antibody assay proved to be more sensitive for the detection of hepatitis A virus from fecal specimens as well as for anti-hepatitis A virus immunoglobulin G (IgG) and IgM in sera.