characteristic features in common with the genome of other retroviruses: long terminal repeats (L TR), and coding regions for internal proteins (gag), for re- verse transcriptase (pol), and for glycosylated virion surface proteins (env) , ar- ranged in the sequence gag, pol, env from the 5′ to the 3′ end of the genome. However, the HTL V genome also contains some specific features not shared with all other retroviruses: the LTR regions are unusually long (745 base pairs, with 298 base pairs constituting the R region), but unlike the long L TRs of mouse mammary tumor viruses, they do not contain open reading frames. A stretch of noncoding sequences separates the gag and the pol genes. Most interestingly, the HTLV genome contains a region between the 3′ end of the env gene and the L TR, called the p X region, that encompasses four open reading frames. Leukemic T cells freshly obtained from patients contain the HTL V provirus but usually do not express it. However, once established in culture, these cells produce viral proteins and release type C particles. Likewise, T cells infected and transformed by HTL V in vitro synthesize virus. Such producing cell lines have been widely used in seroepidemiological surveys and continue to be of importance for detailed studies of viral proteins and nucleic acids.
المزيد من الكتب الإلكترونية من نفس المؤلف (المؤلفين) / محرر
45٬036 كتب إلكترونية في هذه الفئة
