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Background: Human T-lymphotropic virus type 4 (HTLV-4) is a new deltaretrovirus recently identified in a primate hunter in Cameroon. Limited sequence analysis previously showed that HTLV-4 may be distinct from HTLV-1, HTLV-2, and HTLV-3, and their simian counterparts, STLV- 1, STLV-2, and STLV-3, respectively. Analysis of full-length genomes can provide basic information on the evolutionary history and replication and pathogenic potential of new viruses. Results: We report here the first complete HTLV-4 sequence obtained by PCR-based genome walking using uncultured peripheral blood lymphocyte DNA from an HTLV-4-infected person. The HTLV-4(1863LE) genome is 8791-bp long and is equidistant from HTLV-1, HTLV-2, and HTLV-3 sharing only 62-71% nucleotide identity. HTLV-4 has a prototypic genomic structure with all enzymatic, regulatory, and structural proteins preserved. Like STLV-2, STLV-3, and HTLV-3, HTLV-4 is missing a third 21-bp transcription element found in the long terminal repeats of HTLV- 1 and HTLV-2 but instead contains unique c-Myb and pre B-cell leukemic transcription factor binding sites. Like HTLV-2, the PDZ motif important for cellular signal transduction and transformation in HTLV-1 and HTLV-3 is missing in the C-terminus of the HTLV-4 Tax protein. A basic leucine zipper (b-ZIP) region located in the antisense strand of HTLV-1 and believed to play a role in viral replication and oncogenesis, was also found in the complementary strand of HTLV- 4. Detailed phylogenetic analysis shows that HTLV-4 is clearly a monophyletic viral group. Dating using a relaxed molecular clock inferred that the most recent common ancestor of HTLV-4 and HTLV-2/STLV-2 occurred 49,800 to 378,000 years ago making this the oldest known PTLV lineage. Interestingly, this period coincides with the emergence of Homo sapiens sapiens during the Middle Pleistocene suggesting that early humans may have been susceptible hosts for the ancestral HTLV- Conclusion: The inferred ancient origin of HTLV-4 coinciding with the appearance of Homo sapiens, the propensity of STLVs to cross-species into humans, the fact that HTLV-1 and -2 spread globally following migrations of ancient populations, all suggest that HTLV-4 may be prevalent. Expanded surveillance and clinical studies are needed to better define the epidemiology and public health importance of HTLV-4 infection. [ABSTRACT FROM AUTHOR]

To assess the risk of nosocomial transmission of human T-cell lymphotropic virus type III/lymphadenopathy-associated virus (HTLV-III/LAV), we prospectively evaluated a cohort of 531 health care workers. One hundred fifty of these employees reported percutaneous or mucous membrane exposures to blood or body fluids from a patient with the acquired immunodeficiency syndrome (AIDS) during the treatment of 238 such patients since 1981. None of these 150 employees had serologic evidence of HTLV-III/LAV infection on follow-up from 6 to 46 months after exposure. Of the 150, 46 were studied immunologically and 29 had lymphocytes cultured for HTLV-III/LAV. Results of all studies were normal. Of the 531 employees, 3 (0.56%) had serologic evidence of HTLV-III/LAV infection. All were seropositive at the time of study entry; none reported adverse nosocomial exposures. All acknowledged membership in one or more established risk groups for AIDS. This study provides strong evidence that the risk of nosocomial transmission of HTLV-III/LAV is extremely low. [ABSTRACT FROM AUTHOR]

Presents research which studied whether porcine xenografts can lead to porcine endogenous retrovirus (PERV) infection of recipients. PERV carried in the pig germline; Exposure of patients to the virus; Methods; Findings; Absence of PERV infections in these patients; Minimum standard for post-transplant surveillance of patients given porcine xenografts.

We investigated 322 North American zoo workers in an anonymous serosurvey for antibodies to simian foamy viruses to establish the potential risk of zoonotic transmission by these retroviruses. 4 of 133 (3%) individuals who worked specifically with mammals including primates were seropositive, primarily with chimp-like viruses, indicating the importance of work practices to reduce exposure to these agents. [ABSTRACT FROM AUTHOR]