Rachanee Cheingsong-Popov

HUMAN IMMUNODEFICIENCY VIRUS INFECTION IN TWO COHORTS OF HOMOSEXUAL MEN: NEUTRALISING SERA AND ASSOCIATION OF ANTI-GAG ANTIBODY WITH PROGNOSIS

Sequential sera from 48 subjects infected with human immunodeficiency virus type I (HIV-I) were examined over 36 months for the presence of neutralising antibodies, and for specific anti-gag (p24) and anti-env (gp41) antibodies to HIV-I. Results were interpreted in terms of clinical outcome during the period 1982/3 to 1985/6. HIV-I-infected subjects who remained symptom-free, by comparison with those who manifested AIDS or AIDS-related complex (ARC), had a significantly higher titre of anti-p24 antibodies throughout the 3 years, as measured by competitive enzyme-linked immunosorbent assay and radioimmunoprecipitation. The symptomless subjects also showed a trend towards an increasing neutralising antibody titre with time. There was no relation between anti-gp41 titre and clinical outcome, nor an independent relation between anti-p24 and neutralising titre. A lower or falling titre of anti-p24 antibody was associated significantly with clinical progression, up to 27 months before development of AIDS/ARC.

PREVALENCE OF ANTIBODY TO HUMAN T-LYMPHOTROPIC VIRUS TYPE III IN AIDS AND AIDS-RISK PATIENTS IN BRITAIN

2000 persons in the UK were examined serologically for antibodies to human T-lymphotropic virus type III (HTLV-III). Sera reacting in a membrane immunofluorescence assay (IFA) to HTLV-III were also positive when tested against cells infected with lymphadenopathy virus (LAV-1), and cross-adsorption tests indicated that these retroviruses are probably identical. A competitive radioimmunoassay (RIA), which was wholly concordant with IFA, was used to screen the sera. 30/31 patients with the acquired immunodeficiency syndrome (AIDS) were seropositive, as were 89% patients with persistent generalised lymphadenopathy (PGL), 17% symptomless homosexual men, 34% haemophiliacs receiving pooled clotting factors, and 1.5% intravenous drug abusers. None of more than 1000 unselected blood donors was seropositive. These data confirm the close association between HTLV-III and AIDS and PGL and show that infection with HTLV-III is also prevalent in the populations in whom these syndromes are most likely to develop. However, it would be unwise to presume that AIDS will necessarily develop in seropositive subjects.

LOW PREVALENCE IN THE UK OF HTLV-I AND HTLV-II INFECTION IN SUBJECTS WITH AIDS, WITH EXTENDED LYMPHADENOPATHY, AND AT RISK OF AIDS

Antibodies reacting selectively with human T-cell leukaemia virus type I (HTLV-I) were detected in approximately 5% patients with extended lymphadenopathy syndrome (ELAS) and in less than 1% of unselected homosexual patients and drug abusers. None of 22 patients with acquired immunodeficiency syndrome (AIDS) had HTLV-I antibodies and neither did 85 haemophiliacs and 940 blood donors. 3 out of 113 drug addicts had high titres of antibodies to human T-cell leukaemia virus type II (HTLV-II). A T-cell line was derived from 1 of the seropositive ELAS patients. This line was found to be infected with, and releasing, HTLV-I. Infection by HTLV-I and HTLV-II retroviruses thus occurs more frequently in ELAS patients and drug addicts than in the UK population as a whole, but the low prevalence of these infections in ELAS and AIDS patients indicates that these two strains of lymphotropic retroviruses have no aetiological role in ELAS and AIDS.

HTLV-III serology distinguishes atypical and endemic Kaposi's sarcoma in Africa.

Serum samples from African patients with Kaposis sarcoma and acquired-immuno-deficiency-syndrome-related (AIDS-related) disorders and from normal subjects in Uganda and Zambia were tested for antibodies to the human T-lymphotropic retroviruses (HTLV) types I, II, and III. Nearly 90% of patients with AIDS-related disorders or with atypical, aggressive Kaposis sarcoma were seropositive for HTLV-III in both countries, whereas only 17% of patients with classic endemic Kaposis sarcoma were seropositive. Among the controls 20% were seropositive for HTLV-III in Uganda but only 2% in Zambia. None of the subjects tested had antibodies to HTLV-I or HTLV-II. These results are further evidence of the emergence of a clinically atypical form of Kaposis sarcoma in Africans, which resembles that seen in American patients with AIDS, and which is associated with HTLV-III infection. The low frequency of antibodies to HTLV-III in the normal Zambian population together with the first appearance of HTLV-III-associated diseases during the past 2 years suggests that this virus is new to Zambia, although it may have been present in Uganda for longer.

Identification of an env G subtype and heterogeneity of HIV-1 strains in the Russian Federation and Belarus

ObjectiveTo identify HIV-1 envelope sequence subtypes in infected individuals from the Russian Federation and Belarus. PatientsA cohort of children infected after exposure to non-sterile needles during the 1988–1989 HIV-1 epidemic in southern Russia (n = 20) and HIV-1-seropositive individuals from Russia (n = 1) and Belarus (n = 7) infected via sexual transmission. MethodsDNA samples derived from peripheral blood mononuclear cells were analysed for their HIV-1 genotypes by the heteroduplex mobility assay (HMA). The 1.3 kilobase-pair env gene fragments encoding a portion of gp120 were amplified by nested polymerase chain reaction, cloned and sequenced. The env sequences derived from these patients were aligned and phylogenetic neighbour-joining and maximum parsimony-derived trees generated. ResultsThe env sequences derived from eight individuals infected in Russia and Belarus belong to subtype A (one), B (four), C (two), and D (one). Sequences derived from children, infected during parenteral manipulations in southern Russia, and one mother were closely related, but highly divergent, as a group, from all prototypic strains (genetic divergence, 17.2–22.9%). However, they clustered together with env sequences of the V1525 and LBV21–7 isolates from Gabon, recently described to be members of a new HIV-1 env subtype G. ConclusionExtensive heterogeneity of HIV-1 subtypes was evident in the Russian Federation and Belarus. Our data also support the existence of an HIV-1 env genetic subtype G, and such isolates are now apparently present on both the African and European continents. These variants were identified through V3 peptide enzyme-linked immunosorbent assay screening and subsequent HMA analysis. The combination of these techniques represents a model for screening HIV variants within a large population.

Immunization of human HIV-seronegative volunteers with recombinant p17/p24:Ty virus-like particles elicits HIV-1 p24-specific cellular and humoral immune responses.

ObjectiveTo evaluate the immune response to HIV-1 p24 generated in vivo by p17/p24:Ty virus-like particles (p17/p24:Ty-VLP) by examining the lymphoproliferative and antibody (Ab) responses to HIV-1 p24, as well as Gag-specific cytotoxic T lymphocytes (CTL), in HIV-seronegative volunteers immunized with hybrid p17/p24:Ty-VLP. Design and methodsSixteen HIV-seronegative volunteers were immunized with p17/p24:Ty-VLP at two dose levels (100 or 500

Molecular epidemiology of HIV-1 in the former Soviet Union: analysis of env V3 sequences and their correlation with epidemiologic data.

mU.g) and monitored for the following 48 weeks for production of anti-p24 and anti-p17 Ab, in vitro lymphoproliferative responses to HIV-1 p24 and p17, and in vitro CTL responses to HIV-1 Gag. ResultsTwelve out of the 16 volunteers had significant p24-specific proliferative responses, with volunteers on the higher dose schedule exhibiting earlier proliferative responses than those on the lower dose schedule. Proliferative responses in both volunteer groups were similar in overall magnitude but appeared at different times during the immunization schedule. Anti-p24 Ab were detected in six out of the nine individuals in the lower dose group and in five out of the seven in the higher dose group. There was a good correlation between the presence of p24-specific Ab and the detection of lymphoproliferative responses to the p24 protein in peripheral blood mononuclear cells isolated from the same individuals. Anti-p17 Ab were detected in five volunteers. No Gag-specific CTL responses were detected. ConclusionWe conclude that hybrid HIV-1 p17/p24:Ty-VLP are capable of inducing both cellular and humoral immunity to HIV-1 Gag p17 and p24 components and are worthy of further study as a potential HIV immunotherapeutic.

Neutralization of primary and T-cell line adapted isolates of human immunodeficiency virus type 1: role of V3-specific antibodies

ObjectiveTo investigate the HIV-1 V3 sequence diversity in the former Soviet Union in 30 subjects infected with HIV-1 via different modes of transmission. PatientsA cohort of children infected after exposure to nonsterile needles during the epidemic in 1988–1989 in southern Russia (Elista, n = 12 and Rostov-on-Don, n = 10), and eight HIV-seropositive subjects from Belarus (Minsk), infected via sexual (n = 7) and parenteral (n = 1) infection. MethodsThe HIV-1 V3 encoding region was amplified by nested polymerase chain reaction on DNA of primary peripheral blood mononuclear cells collected from the study subjects and then cloned and sequenced. ResultsThe alignment of 127 V3 sequences from 22 patients in the cohort group demonstrated common consensus sequences in both the Elista and Rostov samples. The average means of interperson variation were 5.9 and 6.6% in Elista and Rostov subjects, respectively, and comparable to the mean intraperson variation. The average mean interperson variation between nucleotide sequences of HIV patients infected through sexual transmission was considerably higher (14.9%). ConclusionV3 sequence analysis confirms the epidemiologic data which support the transmission of HIV-1 in children from a single source, and suggests the infection of a mother from her parenterally infected child. Furthermore, the genetic variability of HIV-1 V3 in the noncohort group was particularly divergent indicating the heterogeneity of the virus circulating in the former Soviet Union.

Lack of correlation between V3-loop peptide enzyme immunoassay serologic subtyping and genetic sequencing

The role of the third variable domain (V3) of gp120 in the neutralization of primary and T-cell line adapted (TCLA) strains of human immunodeficiency virus type 1 (HIV-1) by serum from HIV-1-infected individuals was investigated. A primary virus isolate, M2424/4, when adapted to H9 cells, was more sensitive to neutralization on MT2 cells than the same stock passaged in PBMC. Neutralization of the PBMC-passaged stock by V3-specific MAbs was abrogated by addition of V3 (MN) peptide. However, exogenous V3 (MN) peptide failed to reduce the neutralization of this isolate on PBMC, or MT2 cells, by high titre anti-HIV-1 polyclonal human sera in contrast to the extensive reduction of neutralization by the same sera on MT2 cells using the prototype MN strain (4- to > or = 24-fold) and the TCLA M2424/H9 isolate (2- to 8-fold). These results indicate that the neutralization of primary virus isolates by serum from HIV-1-infected individuals is not significantly mediated by V3-specific antibodies.

Development of HIV-1 group-specific neutralizing antibodies after seroconversion

Objective:To compare the performance of V3-loop peptide enzyme immunoassay (PEIA) methodologies from four different laboratories for subtyping HIV-1, and to determine the causes for the lack of correlation between V3-loop PEIA serotyping and subtyping by sequencing. Materials and methods:Synthetic peptides derived from the amino-acid consensus sequences of the V3-loop of group M strains representing genetic subtypes A–F as well as reference strains were evaluated in PEIA by four different laboratories for their ability to accurately determine the subtype in a panel of 85 sera obtained from persons infected with known HIV-1 subtypes (28 subtype A, 34 subtype B, four subtype C, 10 subtype D, seven subtype F, one each of subtype H and G). Furthermore, the V3 loop of the corresponding virus was compared with the V3 loop of the peptides used in PEIA. Results:The correlation between HIV-1 subtyping by sequencing and V3-loop PEIA from the different laboratories varied considerably for the different HIV-1 subtypes: subtype A (46–68%), B (38–85%), C (75–100%), D (29–50%), and F (17–57%). A 70% agreement between PEIA and sequencing subtypes was observed for samples with the concordant presence of the same octameric sequences in the V3 loop of the virus and the V3 loop of the peptide used in PEIA; however, only 42% of specimens with different V3-loop octameric viral and peptide sequences yielded concordant results in V3-loop serotyping and genetic subtyping. Conclusion:Our results indicate that V3-loop PEIA methodologies used in different laboratories correlate poorly with genetic subtyping, and that their accuracy to predict HIV-1 subtypes in sera of Belgian individuals infected with different HIV-1 subtypes (A, B, C, D, F, G and H) vary considerably. The poor correlation between serotyping and genetic subtyping was partly due to the simultaneous occurrence of subtype-specific octameric sequences at the tip of the V3 loop of viruses belonging to different genetic subtypes.