Western blots showing differential antibody reactivity to the three FIV viral antigens. Lanes 14 and 15 contain serum from a known FIV-positive (Western blotting and PCR) and a known FIV-negative lion, respectively. Lanes 1 to 5 contain serum from seropositive and seroindeterminate hyenas. Lanes 6 to 10 contain serum from leopards that have strong antibody response to FIV-Ple and variable reactions to FIV-Fca and FIV-Pco. Lanes 11 to 13 contain serum from lions that have strong antibody responses to FIV-Ple and weak or negative antibody responses to the other two antigens.

(a) Phylogenetic tree for FIV pol-RT nucleotide sequences (476 bp included in analysis). Shown here is the single ML tree. MP, ME (neighbor joining based on the Tajima Nei algorithm for distance measure), and Bayesian trees gave similar topologies. Bootstrap values and posterior probabilities are included at all nodes with bootstrap support (ML/ME/MP/Bayesian). Taxa are designated with the species code followed by the source animal identification number. Sequences downloaded from GenBank for comparison are boxed; all other sequences are novel. A single asterisk indicates a sequence obtained from a captive but wild-born animal; a double asterisk indicates a sequence obtained from a captive-born animal. All other novel sequences are from free-ranging animals. Analysis used empirical base frequencies, an estimated shape parameter of 0.6618, and an estimated substitution matrix as follows: A/C = 2.0642, A/G = 7.2581, A/T = 1.4798, C/G = 4.0169, C/T = 14.0129, and an estimated proportion of invariant sites of 0.1525. (b) Alignments of the predicted amino acid translation products of FIV sequences from individual animals. Single-letter amino acid codes are used. Only variable amino acids are included. Dashes indicate missing data or a gap introduced to optimize the alignment. Sites that distinguish multiple FIV strains from each other are shown as black letters on a grey background, and species-specific differences are shown as white letters on a black background. (c) Phylogenetic tree for FIV pol-RT amino acid sequences (159 amino acid residues were included in the analysis). Shown here is the single maximum likelihood tree with maximum likelihood bootstraps from 1,000 replicates. Abbreviations are as for panel a.

A schematic representing the positions of the primers used for PCR confirmation on the FIV genome. The “5′ position” reflects the position with respect to FIV-Fca Petaluma strain (accession number 323933). Single round and nested primer sets that produced FIV sequence from at least one animal are described. LTR, long terminal repeat; RT, reverse transcriptase; IN, integrase.

Prevalence and distribution of FIV seroreactivity in free-ranging and captive but wild-born animals. The dark portion of the bar represents seropositives and the white portion represents seroindeterminates, giving conservative and liberal estimates of total seroprevalence of FIV. The number of animals tested for each species is given in parentheses. A black star indicates that PCR verification has been obtained from at least one free-ranging individual for that species. A white star indicates that PCR verification has been obtained from at least one captive but wild-born individual for that species. (a) Percent seroreactivity in African carnivores (excluding African golden cat, sand cat, and black footed cat, for which there were no wild-born samples). (b) Percent seroreactivity in American felids (excluding kodkod and Canadian lynx, for which there were no wild-born samples). (c) Percent seroreactivity in Eurasian felids (excluding lynx, bay cat, rusty spotted cat, and Chinese desert cat, for which there were no wild-born samples).