Correlation between seroreactivity to HIV-1 V3 loop peptides and male-to-female heterosexual transmission

Human immunodeficiency virus type 1 (HIV-1) plasma load discrepancies between the Roche COBAS AMPLICOR HIV-1 MONITOR Version 1.5 and the Roche COBAS AmpliPrep/COBAS TaqMan HIV-1 assays

We compared plasma viral load values obtained with COBAS AMPLICOR human immunodeficiency virus type 1 (HIV-1) MONITOR version 1.5 and with COBAS TaqMan HIV-1 assays. Mean values were 4.2 and 2.9 log(10) copies/ml, respectively, showing the lack of agreement between the two assays.

Reproductive choice in individuals HIV-1 infected in south eastern Italy

OBJECTIVE

To evaluate the impact of counseling on reproductive choices in seropositive women in South-Eastern Italy.

SETTING

University Hospital, Apulia region, South-Eastern Italy, tertiary referral center for high risk obstetrics and infectious diseases.

METHODS

Between March 1985 and December 1996, two hundred and twenty-five HIV-infected women, receiving treatment at our clinic for infectious diseases were enrolled. They were all regularly given treatment and counseling and their sexual partners, if negative, tested for HIV-1 antibodies. Their reproductive choices and their attitude toward pregnancy were recorded and analyzed.

RESULTS

Seventy-six pregnancies were observed during this period in 76 women. Twenty-one of these women (27.7%) decided to terminate the pregnancy. Women that were intravenous drug users or with a longer history of known seropositivity were more likely to have a termination. A decreasing trend in the request of abortion was observed with time.

CONCLUSIONS

The data show that the scenario of HIV-infected women is changing in our setting. As a consequence, many seropositive women deliberately choose to have a pregnancy and factors different from those we expect to be modified by the counseling influence their reproductive choice. They should be taken into account in the management of these women before and during pregnancy.

Biological correlates of HIV-1 heterosexual transmission

OBJECTIVES

To study the role of HIV-1 biological phenotype, viral load and neutralizing antibodies in male-to-female heterosexual transmission of HIV-1.

METHODS

Seven transmitting and seven non-transmitting HIV-1-seropositive heterosexual male index cases were included in the present study. All couples had engaged in unprotected sex for a period of over 1 year. Transmission was defined by the seroconversion of the female sexual partner. Virus isolates were tested in MT-2 cells for replication and syncytia induction. HIV-1 RNA plasma load was measured by the branched DNA technique. Serum neutralizing activity to primary HIV-1 isolates was tested by using peripheral blood mononuclear cells (PBMC) as target cells.

RESULTS

Non-transmitting index cases had a lower HIV-1 RNA concentration in plasma than transmitting index cases. Non-transmitting index cases also tended to have serum neutralizing activity with broad specificity and to have viruses with low replicative capacity, as characterized by 50% infectious dose titres in PBMC and by the lack of MT-2 tropism.

CONCLUSIONS

The results indicate that plasma viral-RNA load is a marker for transmission. Moreover, an interplay between the host immune response and viral replication may modulate the level of viral load and thereby influence HIV-1 transmission.

Analysis of genetic heterogeneity, antigenicity, and biological characteristics of HIV-1 in a maternal transmitter and nontransmitter patient pair

To obtain insight into the factors involved in vertical transmission, we compared the sequence diversity, seroreactivity, and biological characteristics of human immunodeficiency virus type 1 (HIV-1) derived from a transmitter and nontransmitter mother pair. Forty-two clones from the transmitter and 20 from the nontransmitter, spanning the principal neutralization determinant (PND) of the env gene, were sequenced and analyzed. The intrapatient sequence variation in transmitter and nontransmitter viruses was 12% and 36%, respectively, and the interpatient variation was 38%. In an effort to correlate immune responses to viral genetics, we analyzed the sera from these patients against a number of V3 peptides from known HIV-1 isolates. We observed that (i) both the transmitter and nontransmitter sera demonstrated higher binding to V3 peptides based on SF-2 and MN sequences than to IIIB and Z6 isolates; (ii) the vertical transmission of HIV-1 is correlated with the absence of high maternal antibody responses to the PND; and (iii) the high-affinity binding of the sera to SF-2 and MN V3 peptides correlated with the sequence analysis, indicating that the V3 sequences from both patients are more closely related to ADA, SF-162, and MN than to IIIB or Z6. Biological analysis of the viruses from these patients demonstrate that the transmitters' viruses infect a number of T-cell lines in vitro, whereas the nontransmitter viruses do not infect cell lines or the primary lymphocytes.

HIV-1 subtypes and male-to-female transmission in Thailand

We examined the risk factors for heterosexual transmission of HIV in a case-control study of couples in Thailand. 90 HIV-positive men and their regular sex partners were enrolled at the immune clinic, Chulalongkorn Hospital, where 92% of male index cases had HIV-1 serotype A (subtype E). Most index cases had acquired HIV through sexual intercourse. 95 couples were enrolled at 15 detoxification clinics, where 79% of them had HIV-1 serotype B (subtype B). Most men had acquired HIV through injecting drug use (IDU).

Primary in vitro immunization with multimeric synthetic peptides of HIV-1 envelope glycoproteins: generation of neutralizing human monoclonal antibodies

Peripheral blood lymphocytes from healthy HIV-1 seronegative donors were immunized in vitro with the following synthetic peptides: (i) an octameric poly-L-lysine conjugated peptide of the HIV-1MN V3 loop and (ii) a resin bound synthetic peptide aa642-665 of HIV-1 gp41. Lymphoblastoid cell lines (LCL) were obtained by immortalization with Epstein-Barr virus (EBV). We produced four LCL secreting human monoclonal antibodies (HuMoAbs) of the IgM isotype: three were directed against the V3 domain (FC10, FC81 and CF41) and one against aa642-665 (CA45C). Two of these HuMoAbs (FC81 and CA45C) reacted to viral surface antigen on HIV-1-infected cells. All the HuMoAbs inhibited 40-53% of cell fusion induced by HIV-1-infected H9 cells at 5 micrograms/ml. They also neutralized, at lower concentrations, cell-free infection with HIV-1MN, HIV-1IIIB and four primary clinical HIV-1 isolates. No enhancing activity of the HuMoAbs in the presence of complement was observed. The results presented here show the feasibility of generating neutralizing human monoclonal antibodies against HIV-1 by primary in vitro immunization with selected synthetic peptides of HIV-1 envelope glycoproteins. This approach has provided tools for further studies of synergistic neutralization assays, and generated potential immunoglobulin candidates for passive immunotherapy.

The reactivities of HIV-1+ human sera with solid-phase V3 loop peptides can be poor predictors of their reactivities with V3 loops on native gp120 molecules

The binding of HIV-1+ human serum antibodies to solid phase-adsorbed V3 loop peptides from the IIIB, SF-2, and MN isolates was compared with the abilities of the same peptides to inhibit binding of the sera to the homologous or heterologous native gp120 molecules. The reactivities of the sera with the solid-phase peptides were found to be poor predictors of the potencies of the peptides as competitors in solution for antibody binding to the V3 loop in situ. Furthermore, the extent of cross-reaction of HIV-1+ human serum antibodies with the three V3 peptides in solid-phase assays was potently influenced by the presence or absence of nonionic detergent. Because the use of solid-phase V3 peptide assays is widespread, and there is no consensus on the use or omission of detergent, there is considerable potential for confusion. These factors should be considered when interpreting data derived from V3 peptide serology when this method is used to dissect the human immune response to HIV-1 infection. It is also shown in quantitative studies of HIV-1+ serum antibody binding to homologous and heterologous gp120s that the general anti-gp120 antibody response is significantly "type specific" for the homologous gp120.