Specific immune response and pathological findings in BALB/c mice inoculated with recombinant BCG expressing HIV-1 antigen.

Recombinant BCGs (rBCGs) containing extrachromosomal plasmids with different HIV-1 insert sequences: nef, env (V3J1 and E9Q), gag p17 or whole gag p55 were evaluated for their immunogenicity, safety and persistent infection in BALB/c mice. Animal injected with, rBCG-plJKV3J1, rBCG-pSO gag p17 or rBCG-pSO gag p55 could elicit lymphocyte proliferation as tested by specific HIV-1 peptides or protein antigen. Inoculation with various concentration of rBCG-pSO gag p55 generated satisfactory specific lymphocyte proliferation in dose escalation trials. The rBCG-pSO gag p55 recovered from spleen tissues at different time interval post-inoculation could express the HIV protein as determined by ELISA p24 antigen detection kit. This result indicated that the extrachromosomal plasmid was stable and capable to express Gag protein. It was also demonstrated that rBCGs did not cause serious pathological change in the inoculated animals. The present study suggested the role of BCG as a potential vehicle for using in HIV vaccine development.

Lymphocyte and NK cell subpopulations in HIV seronegative Thais.

Lymphocyte subpopulations, i.e. T, B and natural killer (NK) cells including NK cell subsets which express CD16 molecules (with or without co-expression of CD56 molecules) and NK cell subsets which express CD56 molecules (with or without co-expression of CD16 molecules) were enumerated by two color-flow cytometry in a total of 125 HIV seronegative Thai adults. The study demonstrated relatively low CD4 counts in the subjects, i.e. 26.3% of them had a CD4 count of less than 500 cells/microl. In contrast, their NK cell counts were relatively high. Statistical analyses of the percentage values showed that females had significantly higher CD3 (total T cells), but lower NK cell counts as compared to males (p < 0.05). Regarding age variation, an increase of 1.1% of CD4 cells per decade was seen. It was roughly estimated that about 86% of NK cells harbored both CD16 and CD56 molecules. Collective data from several studies including the present one suggest that high NK cell counts may be a compensation for low CD4 cell counts in Mongoloid people. Thus, the role of NK cells in the defense cascade against viral infections, especially human immunodeficiency virus infections deserves further investigation.

Characteristic of HIV-1 in V3 loop region based on seroreactivity and amino acid sequences in Thailand.

The third variable (V3) domain of the envelop (env) protein has been used for determining genetic subtype and phenotypic characteristics of human immunodeficiency virus type 1 (HIV-1) isolates. Based on the seroreactivity of the HIV-1 subtype by V3 peptide binding enzyme immunoassay (EIA) of 351 samples obtained in 1998 from HIV-1 infected individuals and AIDS patients, we found that 283 (80.6%) were subtype E, 20 (5.7%) were subtype B, 28 (8.0%) were cross-reactive between both types and 20 (5.7%) were non-typeable. The degree of seroreactivity of HIV-1 subtype E decreased significantly when the amino acid at the crown of the V3 loop was substituted from a GPGQ motif to GPGR motif. Interestingly, AIDS patients who had V3 sequences of subtype E as GPGR motif had a stronger immunoreactivity to GPGQ motif peptides than to GPGR motif peptides, in contradiction for their proviral sequences. The results suggested that mutations in the V3 loop may lead to a changed immunoreactivity that makes HIV-1 mutants unrecognizable or allow escape from the primary immune response by means of neutralizing sensitivity. In connection with vaccine development, it should be pointed out that the combination of V3 sequencing and peptide EIA could provide a novel approach to obtain a primarily infected virus sequence as a target for a preventive AIDS vaccine.