Immunization with HIV-1 subtype B gp160-DNA induces specific as well as cross reactive immune responses in mice.

BACKGROUND & OBJECTIVES: HIV-1 gp160 is an important structural protein for the virus cell interaction and virus entry. Therefore, it is regarded as the most important target for HIV-1 vaccine development. In this study we investigated the use of HIV-1 gp160-DNA construct in eliciting specific and cross reactive cell mediated immune response in mice. METHODS: DNA segment encoding env, tat and rev genes of HIV-1 subtype B (strain BRU-2) was amplified and cloned into mammalian expression vector pCI to generate plasmid pCIBRU-TRE. Mice were injected intramuscularly four times at biweekly intervals with 100 micrograms/dose of pCIBRU-TRE in normal saline, and subsequently analysed for anti HIV-envelope (env) immune responses. RESULTS: A low antibody level was detected as determined by ELISA after 4 doses. Subsequent inoculations failed to increase the antibody titres significantly. Spleen cells from the immunized mice were used for the detection of cellular immune response by lymphocyte proliferation assays (LPA), in vitro production of cytokines and cytotoxic T lymphocyte (CTL) assays. T cell response which was seen from the second week onwards, persisted even at the end of 24 wk following the last dose. Similar levels of T cell proliferation were observed on stimulation with either homologous or heterologous peptides. Cytokine studies showed a Th1 type of response. A cross clade MHC class I restricted CTL response was observed against target cells stimulated with either homologous or heterologous HIV antigens. INTERPRETATION & CONCLUSION: This study demonstrated that DNA encoding full length HIV-1 env glycoprotein gp160 induces specific as well as cross reactive cell mediated immune responses in mice. However, the induction of antibody response was poor.

An alternative method for in vitro production of HIV-1-specific antibodies

We describe the detection of HIV-1-specific antibody secretion by a 24-h culture of peripheral blood mononuclear cells (PBMC) stimulated with disrupted inactivated whole virus absorved onto commercial ELISA microwell plates. The method showed high sensitivity and specificity and was capable of accurately detecting HIV-1 infection early after birth (9 of the 19 patients were < 3 years old) because maternal antibodies do not iterfere by giving false-postive results. No false-positive results were obtained with PBMC from 24 HIV-1-seronegative asymptomatic individuals and no false-negative results were obteined for 10 seropostive adult patients (16-46 years pf age). This rapid, relatively low cost, simple, highly sensitive and specific assay can be extremely useful for the early diagnosis of pediatric AIDS cases