In vitro characterization of FIV-pPPR, a pathogenic molecular clone of feline immunodeficiency virus, and two drug-resistant pol gene mutants.
OBJECTIVE
To compare in vitro replication kinetics and nucleoside analog susceptibilities of a natural feline immunodeficiency virus (FIV) isolate (FIV-Maxam), a molecular clone of FIV (FIV-pPPR), and two (-)-beta-L-2',3'-dideoxy-3'-thiacytidine- (3TC-) resistant mutants of FIV-pPPR.


METHODS
Peripheral blood mononuclear cells (PBMC) from 4 specific-pathogenfree cats.


METHODS
Two point mutations corresponding to mutations of human immunodeficiency virus type 1 (HIV-1) were engineered into the highly conserved YMDD motif of the reverse transcriptase- (RT-) encoding region of the FIV-pPPR pol gene. Replication kinetics and nucleoside analog susceptibilities of FIV-Maxam, FIV-pPPR, and the 2 mutant viruses were measured in vitro, using feline PBMC.


RESULTS
Replication kinetics and nucleoside analog susceptibilities were similar between FIV-Maxam and FIV-pPPR. However, FIV-Maxam was significantly more susceptible to 3TC. A methionine-to-valine mutation at codon 183 (M183V) of the RT-encoding region of the pol gene of FIV-pPPR conferred high-level phenotypic resistance to 3TC and cross-resistance to the related compound (-)-beta-L-2',3'-dideoxy-5-fluoro-3'-thiacytidine.


CONCLUSIONS
Similarities between FIV-Maxam and FIV-pPPR suggest that results of studies performed using FIV-pPPR will have relevance to natural FIV infection in cats. In vitro evaluation of nucleoside analog susceptibilities of FIV-Maxam may help determine concentrations of nucleoside analogs required for effective treatment of FIV-infected cats.


CONCLUSIONS
3TC resistance of FIV-pPPR M183V was similar in magnitude to that of HIV-1 M184V, a mutant described in infected humans treated with 3TC. Thus, FIV-pPPR M183V may be a useful model for studying the in vivo effects of 3TC resistance on lentivirus pathogenesis.
McCrackin Stevenson
M A
MA
Division of Biological Sciences, College of Arts and Sciences, University of Montana, Missoula 59812, USA.
McBroom
D G
DG
D000818:Animals; D000956:Antigens, Viral / Q000032:analysis / Q000096:biosynthesis; D002415:Cats; D003001:Cloning, Molecular; D004279:DNA, Viral / Q000737:chemistry; D004352:Drug Resistance, Microbial / Q000235:genetics; D016181:Feline Acquired Immunodeficiency Syndrome / Q000188:drug therapy / Q000821:virology; D005260:Female; D015751:Genes, pol / Q000235:genetics*; D016089:Immunodeficiency Virus, Feline / Q000187:drug effects* / Q000235:genetics* / Q000502:physiology; D007700:Kinetics; D019259:Lamivudine / Q000494:pharmacology; D008297:Male; D016297:Mutagenesis, Site-Directed; D017354:Point Mutation; D016133:Polymerase Chain Reaction / Q000662:veterinary; D012194:RNA-Directed DNA Polymerase / Q000187:drug effects / Q000235:genetics / Q000378:metabolism; D018894:Reverse Transcriptase Inhibitors / Q000494:pharmacology*; D013047:Specific Pathogen-Free Organisms; D014779:Virus Replication / Q000502:physiology
D000956:Antigens, Viral; D004279:DNA, Viral; D018894:Reverse Transcriptase Inhibitors; D019259:Lamivudine; D012194:RNA-Directed DNA Polymerase