Studies of deltaretrovirus RNA packaging, infectivity and drug susceptibility
Deltaretrovirus, a genus of Retroviridae, includes bovine leukemia virus (BLV) and human T-cell leukemia virus types 1 and 2 (HTLV-1 and HTLV-2). These viruses replicate to low titers in their hosts and are poorly infectious in cell culture therefore; information regarding the molecular details of their life cycle is limited. This dissertation extends the knowledge of deltaretrovirus replication. The hypothesis that a region containing the BLV primary and secondary packaging signals(BLV E) was necessary and sufficient for packaging of heterologous RNA into BLV particles was tested. The BLV E was inserted into a non-viral vector to determine if packaging of the non-viral vector RNA would occur. Analysis of viral RNA indicated that the BLV E is necessary and sufficient to allow for packaging of a non-viral vector RNA. The ability of a chimeric murine leukemia virus (MLV) retroviral vector containing the BLV E to be packaged into BLV particles was also analyzed. The second study tested the hypothesis that the long terminal repeats (LTRs) of BLV, HTLV-1 or HTLV-2 would drive expression of the green fluorescent protein gene (gfp) in cells when transactivated by the BLV, HTLV-1 or HTLV-2 Tax proteins, respectively. The HTLV-1 and HTLV-2 Tax proteins efficiently transactivated both the HTLV-1 and HTLV-2 LTRs and were shown to transactivate the BLV LTR at levels that were comparable to that of the BLV Tax. The third study tested the hypothesis that BLV is susceptible to some nucleoside reverse transcriptase inhibitors (NRTI’s) that are used to inhibit human immunodeficiency virus type 1 (HIV-1) replication. BLV was found to be sensitive to low concentrations of dideoxyadenosine (ddA), dideoxyinosine (ddI) and 3’-azido-3’-deoxythymidine (AZT). BLV was found to be sensitive to (-)2’,3’-dideoxy-3’-thiacytidine (3TC) even though it was predicted to be resistant. These data indicate 3TC resistance is more complex than the methionine to valine substitution in the YMDD motif. In summary, this dissertation determined that the BLV E is necessary and sufficient for RNA packaging of heterologous RNAs into BLV particles. Deltaretrovirus Tax proteins were shown to transactivate each other’s LTRs. Finally; this work has demonstrated that BLV is susceptible to NRTIs.
School:The Ohio State University
School Location:USA - Ohio
Source Type:Master's Thesis
Keywords:blv htlv 1 rna packaging indicator cells drug susceptibility nrtis
Date of Publication:01/01/2004