Replication and pathogenesis of the human T-cell leukemia/lymphotropic retroviruses

Novel biopanning strategy to identify epitopes associated with vaccine protection

Identifying immune correlates of protection is important to develop vaccines against infectious diseases. We designed a novel, universally applicable strategy to profile the antibody (Ab) repertoire of protected vaccine recipients, using recombinant phages encoding random peptide libraries. The new approach, termed "protection-linked (PL) biopanning," probes the Ab paratopes of protected vaccinees versus those with vaccine failure. As proof of concept, we screened plasma samples from vaccinated rhesus macaques (RMs) that had completely resisted multiple mucosal challenges with R5-tropic simian-human immunodeficiency viruses (SHIVs). The animals had been immunized with a multicomponent vaccine (multimeric HIV-1 gp160, HIV-1 Tat, and SIV Gag-Pol particles). After PL biopanning, we analyzed the phagotopes selected for amino acid homologies; in addition to the expected Env mimotopes, one recurring motif reflected the neutralizing Ab epitope at the N terminus (NT) of HIV-1 Tat. Subsequent binding and functional assays indicated that anti-Tat NT Abs were present only in completely or partially protected RMs; peak viremia of the latter was inversely correlated with anti-Tat NT Ab titers. In contrast, highly viremic, unvaccinated controls did not develop detectable Abs against the same epitope. Based upon the protective effect observed in vivo, we suggest that Tat should be included in multicomponent HIV-1 vaccines. Our data highlight the power of the new PL-biopanning strategy to identify Ab responses with significant association to vaccine protection, regardless of the mechanism(s) or targets of the protective Abs. PL biopanning is also unbiased with regard to pathogens or disease model, making it a universal tool.

Retroviral coinfections at a New Orleans HIV outpatient clinic

The purpose of the study was to determine the seroprevalence of human T-lymphotropic virus types I and II (HTLV-I and HTLV-II) infections in an outpatient clinic population of human immunodeficiency virus (HIV)-1 infected persons as well as to identify the demographic and clinical characteristics and laboratory results associated with HTLV-I/II infections. During 1993-1995, 854 patients were tested for HTLV-I/II infection on entry into the clinic, of whom 25 were infected with HTLV-I and 35 with HTLV-II. Multivariate analysis revealed that patients with coinfections were more likely to be black, aged over 35 years, and have a history of injection drug use. HIV-1/HTLV-I coinfections were associated with higher median CD8 counts on entry (p < 0.05), and HIV-1/HTLV-II coinfections were associated with higher median percent CD4 counts (p < 0.05) compared with patients infected with HIV only. Coinfection was not associated with an increased diagnosis of AIDS. These findings indicate that HIV-1/HTLV-I/II coinfections are frequently diagnosed and are associated with unique immune phenotypes. Given the lack of information regarding the influence of dual infection on clinical status, differentiation of HTLV-I from HTLV-II infections may be important in understanding the clinical significance of retroviral coinfections.

In situ hybridization detection of HTLV-I RNA in peripheral blood mononuclear cells of TSP/HAM patients and their spouses

This is the first report of the direct detection of HTLV-I RNA in uncultured peripheral blood mononuclear cells (PBMNC's) of patients with tropical spastic paraparesis and HTLV-I-associated myelopathy (TSP/HAM) and their spouses, using the technique of in situ hybridization. Twenty-one Colombian patients were tested, all of whom had antibodies to HTLV-I; the presence of HTLV-I proviral DNA in their PBMNC's was confirmed by the polymerase chain reaction technique. Of the 21 patients 15 had a clinical diagnosis of tropical spastic paraparesis (TSP/HAM), 5 were asymptomatic relatives, and 1 patient had leukemia. In situ hybridization was positive in samples from 5 patients; 2 of these were TSP/HAM patients and the other 3 were healthy wives of TSP/HAM patients. This study demonstrates for the first time that viral RNA is expressed in uncultured PBMNC's of some patients with TSP/HAM in whom proviral DNA is also present; furthermore, the detection of HTLV-I RNA in the blood of female partners of TSP/HAM patients clearly illustrates the high likelihood of HTLV-I transmission through sexual contact.