G. Hunsmann

Two glycopolypeptides with molecular weights 160,000 and 120,000 (gp120) are regularly recognized by human immunodeficiency virus (HIV)-specific antisera in lysates of cells persistently infected with HIV. In the present study, gp120 was characterized as the major envelope glycopolypeptide of HIV. Gp120 was identified as the external viral glycoprotein by radiosequencing and by its presence in purified virus. However gp120 was predominantly shed as a soluble protein into the culture fluid. Furthermore gp120 was precipitated by sera from horses infected with equine infectious anaemia virus (EIAV), but not by sera from uninfected animals. This may indicate conserved epitopes common to the envelopes of HIV and EIAV.

Juvenile rhesus macaques 6 to 18 months of age were experimentally infected by intravenous inoculation with the simian immunodeficiency virus (SIV), the T cell-tropic retrovirus of monkeys related to the human acquired immunodeficiency syndrome (AIDS) virus HIV. The SIV used for inoculation was grown either in normal human peripheral blood lymphocytes in the presence of interleukin 2 or in the human tumour cell line HUT-78. Eight of the macaques died 129 to 352 days post-inoculation with a variety of clinical and pathological findings paralleling those of AIDS in humans. However eight other animals became persistently infected for prolonged periods; these eight macaques remained alive at 537 and 820 days post-inoculation despite persistent lymphadenopathy and our continued ability to isolate SIV. The ability of these monkeys to survive infection correlated directly with the strength of their antibody response to SIV. Infection was also established in macaques using approximately 100 tissue culture infectious doses of HUT-78-grown SIV. There was no correlation between the dose of virus inoculum and either the strength of the antibody response or clinical outcome. These results demonstrate that SIV infection of macaques can be used not only to study acute AIDS but also to mimic the long-term persistent infection seen in carriers of HIV.

Ninety analogues of suramin have been examined for their ability to inhibit the exogenous reverse transcriptase (RT) of human immunodeficiency virus type I (HIV-I). Of these compounds, 57 inhibited the poly(rC).oligo(dG)-dependent RT activity. Three classes of dose-response curves could be discriminated. Allocation of a compound to one class did not correspond with obvious structural features. Twenty-four substances were superior to suramin in our RT inhibition assay. The RT-inhibitory activity of these compounds did not correlate with their effect against filariae or trypanosomes. Preliminary antiviral evaluation in susceptible human T cells inoculated with HIV-I demonstrated in vitro therapeutic efficacy for some compounds with lower drug-related cellular toxicity than suramin. Certain structural features relevant for the RT-inhibitory effect of these compounds were recognized. Predictions are made for the design of more effective RT inhibitors. Such compounds will help to understand the molecular mechanism of reverse transcription and might be useful in the therapy of retroviral infections.

The adult T-cell leukemia (ATL)-associated antigen complex (ATLA) is recognized by serum antibodies of carriers of ATL virus (ATLV). ATLA consists mainly of ATLV polypeptides and their precursors. The sera from 22 ATL patients, 21 healthy carriers and 9 healthy individuals were examined quantitatively by immunofluorescence assay (IF) for ATLA and by a newly developed radioimmunoprecipitation test with purified 125I-gp68, the putative env gene product of ATLV. More qualitative results were obtained by analysis on polyacrylamide gel (PAGE) of immunoprecipitates from lysates of 35S-cysteine-labelled cells producing ATLV, pelleted ATLV and cell-free culture supernatant. The two quantitative assays gave negative results with sera from all normal subjects and a few patients, but detected ATLA antibodies in all the healthy ATLV carriers. An important finding was that sera of patients that gave negative results in one assay gave positive results in the other, and vice versa. In contrast, all sera from ATL patients and healthy carriers, but not normal donors, precipitated ATLV-specific glycopolypeptides, gp68 and gp46 from 35S-labelled materials. But core polypeptides p28, p24, p19 and p15 were precipitated only by sera with IF titers of over 80. Thus, anti-ATLA antibodies in seropositive sera are predominantly directed against glycopolypeptides of ATLV, and the antibody reactivity to ATLA antigens does not differentiate between ATL patients at various stages of the disease and healthy ATLV carriers.