Absence of evidence of infection with divergent primate T-lymphotropic viruses in United States blood donors who have seroindeterminate HTLV test results

BACKGROUND: Recent identification of divergent simian or primate T-lymphotr opic viruses (STLVs; PTLVs) in bonobos (formerly called pygmy chimpanzees; Pan paniscus;viruses: STLVpan-p and STLVpp1664) and a baboon (Papio hamadry as; viruses: STLVph969 or PTLV-L) have raised the possibility of human infe ction with these viruses. Divergent PTLV-infected primate sera show p24 ban ds on HTLV-I Western blots (WBs). It was investigated whether infection by divergent PTLV-like viruses could explain a subset of United States blood d onors who reacted on HTLV-I EIAs and had indeterminate HTLV-I WBs with p24 bands. STUDY DESIGN AND METHODS: Epidemiologic characteristics of 1889 donors with HTLV-I-indeterminate WBs were compared to those of donors with confirmed r etrovirus infections (393 with HIV, 201 with HTLV-I, 513 with HTLV-II) and 1.6 million donors with nonreactive screening tests. To directly probe for infection with divergent PTLVs, 2 HTLV-I-indeterminate donors born in Afric a and 269 representative non-African-born donors with p24 bands on HTLV-IWB s (previously shown to be negative for HTLV-I and -II DNA by PCR) were sele cted for PTLV PCR analysis. DNA from peripheral blood MNC samples was teste d for a proviral tax sequence by PCR using generic primers that amplify HTL V-I, HTLV-II, and the divergent PTLVs. Amplified tax sequences were detecte d by Southern blot hybridization to a P-32-labeled generic PTLV probe. PCR- positive samples could then be typed by hybridization with virus-specific i nternal probes that differentiate HTLV-I, HTLV-II, PTLV-L, and STLVpan-p. RESULTS: In the epidemiologic analysis, HTLV-indeterminate status was indep endently associated with age of at least 25 years (OR = 2.19; 95% CI, 1.93- 2.49), black (OR = 3.27; 95% CI, 2.90-3.67) or Hispanic (OR = 1.82; 95% CI, 1.52-2.16) race or ethnicity, and donation at one blood center (Baltimore) (OR = 1.30; 95% CI, 1.1 1-1.53). None of the 271 HTLV-I WE-indeterminate s amples tested positive by generic PTLV PGR analysis. CONCLUSION: Although the epidemiologic data suggest the possibility of undi agnosed HTLV-I, HTLV-II, or a cross-reactive virus such as PTLV among older , black, and Hispanic blood donors, the PCR data do not support the presenc e of divergent PTLV infection among US blood donors with HTLV-I-indetermina te results.