Defective human T‐cell leukaemia virus type 1 (HTLV‐1) genomes: No evidence in serologically indeterminate german blood donors but new type detected in established cell lines

Abstract

Individuals reactive in antibody screening tests (ELISA) and with one or more reactions to HTLV-1 proteins on Western blotting, but lacking the criteria of a confirmed HTLV infection, are not exceptional in regions with a low prevalence of HTLV-1/-2 infections. PCR analysis of these indeterminate samples, using "diagnostic" pol and tax sets of primers, give negative results. However, expression of HTLV-1 defective proviruses with internal deletions undetectable by PCR with diagnostic primers could have taken place. Seven German HTLV-1 ELISA-reactive blood donors, who showed reactivity also in Western blots against several viral proteins, and twenty haemophiliacs, were examined by nested PCR and/or PCR/Southern hybridisation with primers designed for detection of HTLV-1 defective proviruses. No HTLV-1-specific amplification products were obtained. However, HTLV-1 defective proviruses with large internal deletions were detected in four out of five cell lines established from symptomatic HTLV-1 cases and two in HUT-102 cells. In two amplicons, short inverted rRNA sequences between gag and env fragments of HTLV-1 defective proviruses were revealed. These results do not exclude the presence of defective HTLV-1 proviruses in individuals with indeterminate serology although this is unlikely.

Human T-Lymphotropic virus (HTLV) type I in vivo integration in oral keratinocytes

“…Although some failure during the PCR process could be responsible for a remote possible mistaken interpretation of results; however another real explanation is that defective proviruses would be generated during the infection process to oral keratinocytes. In order to support the last explanation, previous studies report the existence of defective HTLV-1 provirus in lymphocytic infections not only in ATL (9,20,11,15) but also in HAM/TSP patients (29,30,16,14). In this sense our results would be the first to document the existence of defective HTLV-1 provirus in infected oral keratinocytes.…”

Proviral status of HTLV-1 integrated into the host genomic DNA of adult T-cell leukemia cells

“…On the contrary, it remains controversial as to whether the defective virus functions positively or negatively for the development of ATL, because a defective virus may not always be functional (Korber et al. , 1991; Morozov et al ., 2002).…”

Detection of Human T-Lymphotropic Virus (HTLV) tax Sequences in New York City Blood Donors Seronegative for HTLV Types 1 and 2

“…Interestingly, two other studies described persons who are seronegative or seroindeterminate for HTLV-1 and HTLV-2 and who have an illness resembling HAM-TSP; in both studies, the HTLV tax gene sequences were detected while other gene sequences were not (13,17). While defective tax-only proviruses exist in some high-risk groups, a more recent study shows that lymphocytes of serologically indeterminate blood donors do not harbor defective HTLV proviruses (9). Further, several other studies show that low-risk HTLV-seronegative or -seroindeterminate persons, such as blood donors, with no clinical HTLV symptoms had no FIG.…”