ABSTRACT
An infectious molecular clone of simian immunodeficiency virus SIVsm was derived from a biological isolate obtained late in disease from an immunodeficient rhesus macaque (E543) with SIV-induced encephalitis. The molecularly cloned virus, SIVsmE543-3, replicated well in macaque peripheral blood mononuclear cells and monocyte-derived macrophages and resisted neutralization by heterologous sera which broadly neutralized genetically diverse SIV variants in vitro. SIVsmE543-3 was infectious and induced AIDS when inoculated intravenously into pig-tailed macaques (Macaca nemestrina). Two of four infected macaques developed no measurable SIV-specific antibody and succumbed to a wasting syndrome and SIV-induced meningoencephalitis by 14 and 33 weeks postinfection. The other two macaques developed antibodies reactive in Western blot and virus neutralization assays. One macaque was sacrificed at 1 year postinoculation, and the survivor has evidence of immunodeficiency, characterized by persistently low CD4 lymphocyte subsets in the peripheral blood. Plasma samples from these latter animals neutralized SIVsmE543-3 but with much lower efficiency than neutralization of other related SIV strains, confirming the difficulty by which this molecularly cloned virus is neutralized in vitro. SIVsmE543-3 will provide a valuable reagent for studying SIV-induced encephalitis, mapping determinants of neutralization, and determining the in vivo significance of resistance to neutralization in vitro.
Subject(s)
Genes, env , Simian Acquired Immunodeficiency Syndrome/virology , Simian Immunodeficiency Virus/isolation & purification , Amino Acid Sequence , Animals , Antibodies, Viral/immunology , Macaca nemestrina , Molecular Sequence Data , Simian Immunodeficiency Virus/genetics , Simian Immunodeficiency Virus/immunology , Simian Immunodeficiency Virus/pathogenicity , VirulenceABSTRACT
The complete nucleotide sequence of an isolate of puma lentivirus (PLV-14) was obtained by an inverse polymerase chain reaction (I-PCR) technique and confirmed by conventional PCR. Both methods were used to amplify overlapping regions of proviral DNA, for cloning and sequencing, from genomic DNA isolated from PLV-14 infected Florida puma (Felis concolor coryi) peripheral blood mononuclear cells (PBMC). The provirus has a total length of 9100 nucleotides and the genomic organization of presumed protein coding regions are similar to those seen in other members of the lentivirus family, i.e., three large open reading frames gag, pol, and env as well as smaller intergenic regions that apparently encode regulatory proteins vif and 3' rev by positional and sequence similarity to those seen in other lentiviruses. Two additional open reading frames were identified in the env region and their function (if any) is unknown. The length of the PLV-14 long terminal repeat (LTR) was found to be shorter than the LTRs of feline immunodeficiency virus (FIV). The sequence homology between PLV-14 and other lentiviruses demonstrates that PLV-14 is most closely related to FIV from domestic cats. However, the extent of sequence divergence of each retroviral gene segment is large (e.g., percentage sequence similarity between FIV and PLV-14 env is 8% amino acid and 37% nucleotide similarity), indicating relatively ancient divergence of these feline lentiviral genomes.
Subject(s)
Lentivirus/genetics , Amino Acid Sequence , Animals , Base Sequence , Carnivora/microbiology , Gene Products, env/chemistry , Gene Products, gag/chemistry , Genes, Viral , Genes, env , Genes, gag , Genes, pol , Molecular Sequence Data , Open Reading Frames , Phylogeny , Sequence Alignment , Sequence Homology, Amino Acid , Viral Structural Proteins/geneticsABSTRACT
The natural occurrence of lentiviruses closely related to feline immunodeficiency virus (FIV) in nondomestic felid species is shown here to be worldwide. Cross-reactive antibodies to FIV were common in several free-ranging populations of large cats, including East African lions and cheetahs of the Serengeti ecosystem and in puma (also called cougar or mountain lion) populations throughout North America. Infectious puma lentivirus (PLV) was isolated from several Florida panthers, a severely endangered relict puma subspecies inhabiting the Big Cypress Swamp and Everglades ecosystems in southern Florida. Phylogenetic analysis of PLV genomic sequences from disparate geographic isolates revealed appreciable divergence from domestic cat FIV sequences as well as between PLV sequences found in different North American locales. The level of sequence divergence between PLV and FIV was greater than the level of divergence between human and certain simian immunodeficiency viruses, suggesting that the transmission of FIV between feline species is infrequent and parallels in time the emergence of HIV from simian ancestors.