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Frequent infection with zoonotic simian foamy virus (SFV) has been reported among HIV-negative primate hunters in rural Cameroon. Plasma samples obtained from urban commercial sex workers (CSWs; n= 139), patients with sexually transmitted diseases (n = 41), and blood donors (n= 179) in the Democratic Republic of Congo [formerly known as Zaire] and Cameroon were tested for SFV and HIV-1 infection. One CSW and one blood donor were found to be seropositive for both SFV and HIV-1, thereby documenting what are, to our knowledge, the first reported cases of dual SFV and HIV infection. The findings of the present study suggest opportunities for bloodborne and sexual transmission of SFV and highlight the importance of defining the clinical consequences of dual infections. [ABSTRACT FROM AUTHOR]

We examined the efficacy of tenofovir disoproxil fumarate (TDF) in blocking simian human immunodeficiency virus (SHIV) infection in Chinese rhesus macaques. Once weekly for 14 weeks or until a macaque became infected, 12 male macaques were inoculated intrarectally with amounts of SHIVSF162P3 (10 median tissue culture infective doses; 3.8×105 virus particles) that were ∼5-fold higher than the human immunodeficiency virus type 1 RNA levels noted in human semen during an acute infection. Of the 12 macaques, 4 received oral TDF daily, 4 received oral TDF once weekly, and 4 (control animals) received no TDF. The control animals became infected after receiving a median of 1.5 virus inoculations; macaques receiving TDF daily (1 macaque remained uninfected after 14 inoculations) and those receiving TDF weekly became infected after a median duration of 6.0 and 7.0 weeks, respectively. Although infection was delayed in treated macaques, compared with control macaques, the differences were not statistically significant (P = .315); however, the study was limited by the small numbers of animals evaluated and the variability in blood levels of TDF that resulted from oral dosing. These data demonstrate that treatment with oral TDF provided partial protection against SHIV infection but ultimately did not protect all TDF treated animals against multiple virus challenges. [ABSTRACT FROM AUTHOR]

A nonhuman-primate model of human immunodeficiency virus type 1 (HIV-1) infection that more closely emulates human heterosexual transmission by use of multiple exposures to low doses of virus is critical to better evaluate intervention strategies that include microbicides or vaccines. In this report, we describe such a system that uses female pig-tailed macaques exposed vaginally to a CCR5-using simian-human immuno-deficiency virus (SHIV162P3) at weekly intervals. Results of dose-titration experiments indicated that 3 once-weekly exposures to 10 tissue culture infectious doses of SHIV162P3 resulted in consistent transmission of virus and establishment of systemic infection. The efficacy of cellulose acetate phthalate (CAP) as a vaginal microbicide was evaluated by applying it to the vaginal vault of macaques (n = 4) 15 mm before each weekly exposure to SHIV162P3. One conclusion that can be drawn from the data derived from multiple exposures to virus is that CAP prevented infection in 12 of 13 possible chances for infection, over the course of 39 total exposures. Our findings provide a basis to refine monkey models for transmission of HIV-1, which may be relevant to preclinical evaluation for therapeutic interventions. [ABSTRACT FROM AUTHOR]

Provides information on a study which evaluated male genital tract shedding to characterize HIV expression in semen during primary infection. Methods; Virologic characterization after simian/HIV infection; Virus-specific antibody responses and lymphocyte fluctuations during primary infection.

Studies the presence of porcine endogenous retrovirus (PERV) in plasma samples of pigs and in clinical lots of unheated porcine clotting factor VIII concentrate (Hyate:C). Background of the study; Reverse-transcriptase polymerase reaction testing of PERV RNA in pig serum/plasma samples and Hyate:C; RT activity screening in pig serum/plasma samples and Hyate:C products; PERV envelope subtype analysis; Results; Discussion.

Examines the viral and immunologic complications of HIV-positive patients. Determination of whether persistent seronegativity was attributable to immune dysfunction or infection; Results of the in vitro stimulation of peripheral blood mononuclear cells.

Virus load based on levels of functional reverse transcriptase (RT) was measured in plasma from 50 human immunodeficiency virus (HIV) type 1-infected persons, in 87 samples from 10 HIV-1 seroconversion panels, and in 100 uninfected persons by use of Amp-RT, an ultrasensitive RT assay. Of the 50 clinical samples, 38 (76%) were Amp-RT positive, while all uninfected controls were negative. Pearson's correlation coefficient of RNA and RT levels was .73 for all samples, .86 for seroconversion samples, and .49 for clinical samples. Calculated ratios of RT activity to virion RNA varied widely during both early and late stages of infection. Mean RT:RNA ratios in 8 seroconversion panels and in 12 (34.3%) of 35 individual clinical samples were significantly lower than the ratio for a reference virus. However, ratios were stable in individual seroconversions over time. These data demonstrate that RT activity can be used to quantitate plasma virus load and provide evidence of different levels of virion-associated RT among HIV-1-infected persons. [ABSTRACT FROM PUBLISHER]

Human immunodeficiency virus (HIV)-2 differs from HIV-1 in its relative lower transmissibility and pathogenicity. To understand the virologic basis of these differences, the nef gene from HIV-2-seropositive persons was analyzed because of its importance for disease progression in the genetically related simian immunodeficiency virus (SIV[MAC]). Proviral nef sequences from 60 HIV-2-infected persons were amplified from peripheral blood lymphocytes, and nef open-reading frames were screened by a transcription and translation assay for the presence of full-length (32- to 36-kDa) or truncated (<32 kDa) Nef proteins. Overall, 6 (10%) of 60 persons had truncated Nef proteins; of these, 5 were among the 36 asymptomatic subjects (13.9%) and only 1 was among the 24 symptomatic subjects (4.2%) (P =.23). The results of this study document the presence of defective nef genes in HIV-2 infections with a prevalence higher than that previously seen in HIV-1-infected cohorts of long-term nonprogressors or patients with AIDS. [ABSTRACT FROM AUTHOR]

In an ultrasensitive assay for reverse transcriptase (RT), an in vitro-transcribed heteropoly-meric RNA sequence was used as a template and polymerase chain reaction (PCR) amplification with Southern blot hybridization served as a detection system for the cDNA reaction product. The assay, called Amp-RT, detected 9 tested retroviruses in unconcentrated culture supernatants diluted 102- to 105-fold. A comparative analysis using human immunodeficiency virus type 1 (HIV-l) revealed that Amp-RT was 100,000 times more sensitive than the standard RT assay, 10,000 times more sensitive than p24 antigen capture and branched DNA assays, and 100 times more sensitive than RT-PCR or TCID50 assays. Analysis of serum specimens from 42 HIV-l-infected persons by Amp-RT showed that 36 samples (85.7%) were RT-positive. In contrast, 41 serum specimens from persons seronegative for HIV-1 and human T lymphotropic virus types I and II were all Amp-RT-negative. [ABSTRACT FROM PUBLISHER]

Synthetic peptides corresponding with unique regions of the envelope glycoproteins (gp46) of human T cell Iymphotropic viruses (HTLVs)were used in an enzyme immunoassay to determine if HTLV-I and -II infections could bediscriminated. Two synthetic HTLV-Isequence-derived peptides, Env-1 (amino acids 191–215) and Env-5 (amino acids 242–257), reacted with 92% and 100% of the serum specimens (n = 52) from HTLV-I-infected persons, respectively. Although a small percentage (8.6%)of serum specimens from persons infected with HTLV-IIcross-reacted with Env-1, none of these specimens reacted with Env-5. Peptide Env-2 encoded by the envelope region ofHTLY-1I(amino acids 187–210)reacted with serum specimens from both HTLY-I(94%)and HTLV-II (74%)-infected patients, whereas Env-6, another HTLV-II peptide (amino acids 238–254), reacted with <6% of the specimens. Therefore, the Env-5 peptide with amino acid sequence SerProAsnValSerValProSerSerSerSerThrProLeuLeuTyr represents an immunodominant domain of HTLV-I that is recognized by serum antibodies from all HTLV-I-infected persons. Moreover, the Env-5-based ELISA allows a categorical distinction between the closely related HTLV-I and -II infections. [ABSTRACT FROM PUBLISHER]

We investigated 21 patients with chronic fatigue syndrome who were identified through the surveillance system of the Centers for Disease Control and Prevention (CDC) in Atlanta for the presence of several human and animal retroviruses. In addition, we evaluated 21 CDC employee controls matched with the patients for age (±5 years), gender, and race. The viruses tested included human T-lymphotropic viruses types I and II; human spuma retrovirus; simian T-lymphotropic virus type I; simian retroviruses types 1, 2, and 3; bovine leukemia virus; feline leukemia virus; and gibbon ape leukemia virus. Samples of peripheral blood lymphocytes and leukocytes from patients and controls were analyzed in a blinded fashion for retroviral sequences; polymerase chain reaction (PCR) amplification assays and Southern blot hybridization to 32P-la-beled internal oligoprobes were used. All PCR assays were optimized for maximal sensitivity on respective infected cell lines or plasmids, and sensitivity controls were included in each experiment. All samples from patients and controls were negative for the tested retroviral sequences. Our data indicate that none of these retroviruses plays an etiologic role or is a cofactor in the chronic fatigue syndrome illnesses of our study population. [ABSTRACT FROM PUBLISHER]