Abstract:
High genetic diversity is a major contributory factor in the development of drug resistance, in
addition to challenges in diagnosis and treatment monitoring in the therapeutics of human
immunodeficiency virus (HIV) .Within the wide HIV-1 diversity, differences in mutational
frequency, disease progression, drug response and transmission amongst HIV-1 subtypes
have been shown. In spite HIV-1 subtype C (HIV-1C) being the most prevalent variant globally,
none of the available drugs nor screening assays for inhibitory molecules have been developed
targeting the genetics of this important subtype. This study therefore aimed to overexpress and
biophysically characterize HIV-1C reverse transcriptase and protease to serve as reagents in
the development of assays for routine screening of molecules inhibitory to HIV-1C.
Heterologous expression of HIV-1C reverse transcriptase and protease isolates that are
prevalent in South Africa was carried out in Escherichia coli (E. coli (BL21-DE3). The secondary
and tertiary structures of the proteins were determined using, circular dichroism (CD) and
fluorescence spectroscopy respectively. Thereafter, interaction studies to delineate interaction
properties of natural products for possible inhibition of protease were conducted. Furthermore,
in silico studies to determine binding interactions, further confirmed by in vitro binding assays
of a pepsin inhibitor homolog (Bm-33) from Brugia malayi , against protease were also
conducted. Expressed reverse transcriptase and protease from the globally prevalent HIV-1C
were shown to be structurally and functionally intact for application in downstream HIV-1
inhibition assays. Interaction studies on the other hand revealed successful inhibition of the
expressed HIV-1C PR with gallotanin. Furthermore, binding interactions of Bm-33 and HIV-1
PR revealed the first intermolecular interactions of the two molecules displaying possible
inhibition of HIV-1 PR
