HIV genome in peripheral blood mononuclear cells of seronegative regular sexual partners of HIV-infected subjects

Reevaluation of possible outcomes of infections with human immunodeficiency virus

Several lines of evidence indicate that HIV infection can result in several possible incomes, including a very small proportion of individuals whose HIV replication is controlled after treatment interruption (known as HIV posttreatment controllers) or spontaneously without any treatment (known as HIV elite controllers). Both types of individuals are HIV RNA negative but HIV DNA positive, with living virus which can be stimulated ex vivo. A review was conducted to assess the literature on yet rarer cases with detectable integrated HIV DNA without HIV infectious virus in HIV-seropositive or -negative individuals. Three categories of patients were identified: (a) HIV-seropositive individuals with apparent spontaneous cure from their HIV infection, (b) HIV-seronegative children born to HIV-infected mothers and (c) highly exposed seronegative adults. Validity criteria were proposed to assess the presence of integrated HIV DNA as possible or unquestionable in these three categories. Only three articles among the 22 ultimately selected fulfilled these criteria. Among the highly exposed seronegative subjects, some individuals were described as being without integrated HIV DNA, probably because these subjects were not investigated using relevant, highly sensitive methods. Finally, we propose a definition of spontaneous cure of HIV infection based on clinical, immunologic and virologic criteria.

Detection of feline immunodeficiency virus proviral DNA in feline peripheral blood mononuclear cells by the nested two-step polymerase chain reaction

The polymerase chain reaction (PCR) was applied to detect feline immunodeficiency virus (FIV) proviral DNAs in primary peripheral blood mononuclear cells (PBMC). Suitable conditions for PCR amplification were examined to obtain highly sensitive and specific results by simple staining in agarose gel. Specific amplification of FIV proviral DNA in PBMC DNA of FIV-infected cats was achieved by a nested two-step PCR that amplified the DNA first with outer primers and then with inner primers nested within the first primers. PCR amplification using different primers indicated that those based on the gag sequence of the FIV/TM2 strain isolated in Japan were suitable for the detection of FIV genomes in naturally infected Japanese pet cats. By the nested two-step PCR with mixed gag primers of TM2 and Petaluma, isolated in the USA, we could detect FIV genomes in all 11 primary PBMC samples from FIV-seropositive cats tested. The PCR protocol developed here is sensitive and specific for molecular detection of FIV infection in cats.

Detection of feline immunodeficiency virus (FIV) nucleic acids in FIV-seronegative cats

A study was undertaken to determine the rate of viral transmission among naive specific-pathogen-free (SPF) cats living in close contact with feline immunodeficiency virus (FIV)-infected cats. Twenty SPF cats were housed in the same rooms with experimentally FIV-infected seropositive and virus culture-positive cats for 2 to 4 years and were monitored for the presence of FIV nucleic acids and antibodies. Only 1 of the 20 cats became seropositive and virus culture positive and developed signs of disease. Genomic DNA from bone marrow and peripheral blood mononuclear cells (PBMC) of 10 of 19 healthy-appearing seronegative cats became positive for FIV DNA by the polymerase chain reaction. Twenty-eight SPF cats housed as groups in separate quarters and never exposed to FIV-infected cats were uniformly negative for FIV DNA. FIV RNA transcripts were detected in concanavalin A-stimulated PBMC cultures from 4 of 10 FIV DNA-positive, seronegative cats by in situ hybridization. PBMC from three of four naive SPF cats acquired FIV nucleic acids after the cats were transfused with blood and bone marrow from FIV genome-positive, seronegative donors. Three of five FIV-seronegative cats housed for years with naturally FIV-infected cats in a private household were also found to harbor FIV DNA, indicating that the same phenomenon occurred in the field. These findings demonstrate that cats living in close contact with FIV-infected seropositive cats can acquire FIV nucleic acids without developing detectable levels of serum antibodies or disease.

Detection of feline immunodeficiency proviral DNA in peripheral blood lymphocytes by the polymerase chain reaction

Feline immunodeficiency virus (FIV) proviral DNA was detected by the polymerase chain reaction method (PCR). PCR products were detected by gel electrophoresis and ethidium bromide staining. The P-10, P-15 and P-24 regions of the gag gene of FIV were chosen as the target sequences for amplification, and three primer pairs were prepared. The PCR products subjected to amplification with each primer pair were found to possess sites of digestion by a restriction enzyme, as hypothesized. They did not react with feline leukemia virus (FeLV)-infected or feline syncytium-forming virus (FeSFV)-infected cell-derived DNA, and specifically amplified FIV-infected cell-derived DNA. FIV proviral DNA was detected by the PCR method with either primer pair (one-step amplification: single PCR) in DNA derived from peripheral blood lymphocytes (PBL) from 7 of 12 FIV antibody-positive cats. When PCR products in each of the 12 cats were subjected to a second amplification using the same primer pair (two-step amplification: double PCR), FIV proviral DNA was detected in all of the cats. When PBL samples collected from three cats that were negative and three that were positive in the single PCR were cultured for a few weeks in the presence of interleukin 2, FIV proviral DNA was detected in all six cats by the single PCR method. The results suggest that either the use of cultured PBL as the sample or the performance of the double PCR method enables simple and specific detection of FIV proviral DNA in PBL.

Persistence of HIV-1 silent infection in seronegative subjects at high risk

Twenty regular sexual partners of HIV-1 infected subjects, without detectable human immunodeficiency virus (HIV-1) antibody and positive for HIV-1 genome by in situ hybridization (ISH), were selected and studied longitudinally for 6-36 months to estimate the duration of silent infection. During the follow-up period, 10 showed atypical Western Blot (WB) patterns. Two seronegative partners seroconverted. Rapid progress to AIDS was observed in 7 seropositive subjects.

Detection of human immunodeficiency virus type 1 transcripts in peripheral blood lymphocytes by the polymerase chain reaction

A simplified application of the polymerase chain reaction (PCR) to the routine detection of human immunodeficiency virus type 1 (HIV-1) transcripts from peripheral lymphocytes of infected subjects is described. This technique is simpler than previously described assays and was shown to be highly sensitive after ethidium bromide staining of polyacrylamide gel electrophoresis of amplified material. The method can be used for the virologic evaluation of HIV-1-infected subjects, thus allowing early identification of seropositive patients with signs of active infection.

Production of a nef-specific monoclonal antibody by the use of a synthetic peptide

Monoclonal antibodies have been generated against a synthetic peptide of the nef protein of human immunodeficiency virus type 1 (HIV-1) in order to further characterize the biochemical and functional nature of this protein and its role in the control of HIV-1 transcriptional regulation. Earlier studies indicated nef to be a negative regulatory factor for viral transcription, whereas more recent studies report evidence against this original hypothesis. Nef is a protein of 206 amino acids of approximately 27 kD in most HIV-1 isolates; however, in some other isolates a truncated form of 124 amino acids has been described. A peptide sequence of six amino acids, corresponding to a region of the nef protein exhibiting high-sequence homology to thymosin alpha 1 protein, has been synthesized by Merrifield solid-phase methodology. This peptide is coded by a sequence located upstream to the stop codon described in some HIV-1 isolates and then is maintained in both complete and truncated forms of the nef protein. F14.11 is a nef peptide-specific monoclonal antibody (IgG2a/k) exhibiting the ability to recognize natural nef protein in either radioimmunoassay, radioimmunoprecipitation assay, or immunocytochemical analysis. Since F14.11 is able to identify nef protein in the cytoplasm of lymphocytes from HIV-infected seronegative subjects it may prove useful in monitoring the expression of nef during the silent HIV-1 infection.