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RNase H activity and drug resistance to nucleoside and nonnucleoside reverse transcriptase inhibitors
Author(s) -
Pathak Vinay K.,
DelviksFrankenberry Krista A.,
Nikolenko Gali.
Publication year - 2009
Publication title -
the faseb journal
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.709
H-Index - 277
eISSN - 1530-6860
pISSN - 0892-6638
DOI - 10.1096/fasebj.23.1_supplement.331.2
Subject(s) - reverse transcriptase , rnase h , primer (cosmetics) , nucleoside reverse transcriptase inhibitor , rnase p , rna , drug resistance , biology , virology , nucleoside , nucleoside analogue , microbiology and biotechnology , chemistry , genetics , gene , organic chemistry
Antiretroviral nucleoside and nonnucleoside reverse transcriptase inhibitors (NRTIs and NNRTIs, respectively) initially control HIV‐1 infection, but rapid emergence of drug‐resistant variants limits their effectiveness. Elucidating the mechanisms that lead to drug resistance could facilitate better management of antiviral therapy and development of more effective treatments. Toward this end, we previously proposed that the rate of degradation of HIV‐1 RNA by RNase H (rh) defines the time available for reverse transcriptase (RT) to excise an incorporated NRTI from a terminated primer. This novel concept predicted that a reduced rate of template RNA degradation will increase NRTI resistance. Our recent studies have verified key predictions of this model. First, we identified 8 novel mutations in the connection subdomain (cn) of HIV‐1 RT that increased AZT resistance by as much as 536‐fold when the pol domain contains standard thymidine analog mutations (TAMs). Second, we showed that the cn mutations reduced RNase H cleavages in biochemical assays. Third, we demonstrated that the cn mutations increased AZT monophosphate (AZTMP) excision on an RNA template but had minimal effects on AZTMP excision on a DNA template. These studies indicate that including cn and rh portions of RT in clinical genotypic and phenotypic assays could lead to more accurate determinations of viral drug resistance.