ABSTRACT
A highly cytopathic feline immunodeficiency virus, FIV-Oma, was previously isolated from a nondomestic cat. In this report, we describe experiments to characterize its transcription map and examine its Rev activity. The temporal progression of viral gene expression is similar to that of HIV-1. The splicing pattern of viral transcripts was determined by sequence analysis of RT-PCR-amplified viral cDNAs. In vitro transcription and translation of two putative rev cDNAs revealed that they encode at least one 22-kDa protein. The Rev-responsive element (RRE) of FIV-Oma, identified by computer-assisted RNA secondary structure analysis, was inserted into the intron of an HIV-1-derived reporter plasmid and used in a transient transfection assay for Rev activity. Cotransfection of the RRE construct with the two rev cDNA clones significantly increased the expression of the reporter gene linked to the RRE, indicating that both transcripts encode an active Rev protein. The Rev activity of FIV-Oma is 5 to 8 times higher than that of a domestic cat FIV isolate, FIV-PPR. Our experiments also demonstrate the heterologous interaction of FIV-PPR Rev with the FIV-Oma RRE, even though the RREs of the two viruses have very little nucleotide sequence identity.
Subject(s)
Genes, rev , Immunodeficiency Virus, Feline/genetics , Immunodeficiency Virus, Feline/pathogenicity , Animals , Base Sequence , Cats , Chromosome Mapping , Cytopathogenic Effect, Viral/genetics , DNA Primers/genetics , DNA, Complementary/genetics , DNA, Viral/genetics , Molecular Sequence Data , Nucleic Acid Conformation , Polymerase Chain Reaction , Protein Biosynthesis , RNA Splicing , RNA, Messenger/genetics , RNA, Viral/chemistry , RNA, Viral/genetics , Transcription, GeneticABSTRACT
The nucleotide sequence and genomic organization have been determined for a highly cytopathic feline immunodeficiency virus (FIV) isolated from a Pallas' cat. The 9747-bp provirus of this virus, FIV-Oma, has typical lentivirus organization with LTRs, gag, pol, and env open reading frames (ORFs), putative vif and rev ORFs, and an ORF similar to ORF2/ORFA of domestic cat FIV isolates. Although the FIV-Oma provirus is 300 to 600 bp longer than other FIV proviruses, these additional bases are distributed throughout the genome. Phylogenetic analysis of a conserved region of the pol gene suggests that FIV-Oma is more closely related to some of the puma and lion lentiviruses than it is to domestic cat FIV isolates; however, many regions of the genome exhibit extensive nucleotide sequence divergence. None of the eight molecular proviral clones isolated from a genomic library are infectious, but we have constructed an infectious, cytopathic clone of FIV-Oma from subcloned and PCR-amplified fragments of these proviral clones. This clone will be useful for identifying the genetic determinants of FIV-Oma's biological activities.
Subject(s)
Genome, Viral , Immunodeficiency Virus, Feline/genetics , RNA, Viral/analysis , Sequence Analysis, RNA , Amino Acid Sequence , Animals , Base Sequence , Cats , Cell Line , DNA, Viral , Immunodeficiency Virus, Feline/classification , Immunodeficiency Virus, Feline/isolation & purification , Lentivirus/genetics , Molecular Sequence Data , Phylogeny , Proviruses/classification , Proviruses/genetics , Proviruses/isolation & purification , Sequence Homology, Nucleic AcidABSTRACT
A 13-year-old, 4-kg, neutered male Maine coon presented with ascites. Toxoplasma gondii tachyzoites were seen within neutrophils and macrophages, and free within the abdominal fluid. At necropsy, many abdominal organs were positive for feline infectious peritonitis (FIP) antigens using immunohistochemical staining. This apparently is the first report of concurrent toxoplasmosis and FIP in a domestic cat.
