Scientific Publications by FDA Staff

J Infect Dis 2006 Feb 1;193(3):427-37

Human T Lymphotropic Virus Types I and II Western Blot Seroindeterminate Status and Its Association with Exposure to Prototype HTLV-I.

Yao K, Hisada M, Maloney E, Yamano Y, Hanchard B, Wilks R, Rios M, Jacobson S

Jacobson S, NINDS, Neuroimmunol Branch, NIH, Viral Immunol Sect, 9000 Rockville Pike,Bldg 10,Ste 5N214, Bethesda, MD 20892 USA NINDS, Neuroimmunol Branch, NIH, Viral Immunol Sect, Bethesda, MD 20892 USA NCI, Viral Epidemiol Branch, Div Canc Epidemiol & Genet, NIH, Bethesda, MD 20892 USA Johns Hopkins Univ, Dept Biol, Baltimore, MD 21218 USA US FDA, Rockville, MD 20857 USA Univ W Indies, Mona Kingston, Jamaica

Human T lymphotropic virus types I and II (HTLV-I/II) Western blot (WB) seroindeterminate status, which is defined as an incomplete banding pattern of HTLV protein Gag (p19 or p24) or Env (GD21 or rgp46), is commonly observed. To investigate the significance of this finding, we examined HTLV-I/II serostatus and HTLV-I proviral load in 2 groups of individuals with WB seroindeterminate status. Low proviral loads were detected in 42% of patients with neurologic symptoms and 44% of voluntary blood donors. These data suggest that a subset of WB seroindeterminate individuals may be infected with prototype HTLV-I. To confirm this hypothesis, we evaluated HTLV-I/II serostatus and proviral load in prospectively collected specimens from 66 WB seronegative patients who had received HTLV-I-infected blood products by transfusion. Eight individuals developed WB seroindeterminate profiles after the transfusion. In addition, using a human leukocyte antigen type A*201-restricted HTLV-I Tax11-19 tetramer, we detected virus-specific CD8(+) T cells in peripheral blood mononuclear cells from WB seroindeterminate patients. These CD8(+) T cells were effective at targeting HTLV-I-infected cells. Collectively, the results suggest that HTLV-I/II WB seroindeterminate status may reflect a history of HTLV-I exposure. Our findings warrant further investigation of the possible clinical outcomes associated with WB seroindeterminate status.