Phylogenetic Analyses of Novel Squamate Adenovirus Sequences in Wild-Caught Anolis Lizards

Adenovirus infection has emerged as a serious threat to the health of captive snakes and lizards (i.e., squamates), but we know relatively little about this virus' range of possible hosts, pathogenicity, modes of transmission, and sources from nature. We report the first case of adenovirus infection in the Iguanidae, a diverse family of lizards that is widely-studied and popular in captivity. We report adenovirus infections from two closely-related species of Anolis lizards (anoles) that were recently imported from wild populations in the Dominican Republic to a laboratory colony in the United States. We investigate the evolution of adenoviruses in anoles and other squamates using phylogenetic analyses of adenovirus polymerase gene sequences sampled from Anolis and a range of other vertebrate taxa. These phylogenetic analyses reveal that (1) the sequences detected from each species of Anolis are novel, and (2) adenoviruses are not necessarily host-specific and do not always follow a co-speciation model under which host and virus phylogenies are perfectly concordant. Together with the fact that the Anolis adenovirus sequences reported in our study were detected in animals that became ill and subsequently died shortly after importation while exhibiting clinical signs consistent with acute adenovirus infection, our discoveries suggest the need for renewed attention to biosecurity measures intended to prevent the spread of adenovirus both within and among species of snakes and lizards housed in captivity

Phylogenetic analyses of novel squamate adenovirus sequences in wild-caught Anolis lizards.

Adenovirus infection has emerged as a serious threat to the health of captive snakes and lizards (i.e., squamates), but we know relatively little about this virus' range of possible hosts, pathogenicity, modes of transmission, and sources from nature. We report the first case of adenovirus infection in the Iguanidae, a diverse family of lizards that is widely-studied and popular in captivity. We report adenovirus infections from two closely-related species of Anolis lizards (anoles) that were recently imported from wild populations in the Dominican Republic to a laboratory colony in the United States. We investigate the evolution of adenoviruses in anoles and other squamates using phylogenetic analyses of adenovirus polymerase gene sequences sampled from Anolis and a range of other vertebrate taxa. These phylogenetic analyses reveal that (1) the sequences detected from each species of Anolis are novel, and (2) adenoviruses are not necessarily host-specific and do not always follow a co-speciation model under which host and virus phylogenies are perfectly concordant. Together with the fact that the Anolis adenovirus sequences reported in our study were detected in animals that became ill and subsequently died shortly after importation while exhibiting clinical signs consistent with acute adenovirus infection, our discoveries suggest the need for renewed attention to biosecurity measures intended to prevent the spread of adenovirus both within and among species of snakes and lizards housed in captivity

Phylogenetic relationships among adenovirus polymerase sequences inferred using the amino acid models implemented in MrBayes.

<p>The phylogenetic position of newly acquired sequences is indicated in grey. Node support values presented are posterior probabilities (PP): black circles PP>95, grey circles 95>PP>70, and white circles 70>PP>50. To simplify the graphical representation of this result, we pruned from the tree adenoviruses that were drawn from the same host and were strongly supported as monophyletic. When a sequence has been reported from two or more reptilian species, we indicate the infected species with a bracket.</p

Adenovirus sequences analyzed.

<p>Adenovirus sequences analyzed.</p

Reported squamate species in which adenovirus infections have occurred.

1<p>RWC  =  Recently wild caught, ²NA  =  information on source not available, ³LTC  =  long-term captive (possibly including individuals that were born and bred in captivity), ^3aLTC?  =  likely long-term captive, but no information on origins in original publication.</p

Phylogenetic tree for squamate reptiles derived from Townsend et al. (2004).

<p>Black squares indicate clades with previously reported adenovirus infections, white squares indicate clades without previously reported infections, and the gray square indicates the clade from which adenovirus infection is reported in this study.</p

Collecting locations of <i>A. d. ignigularis</i> (square) and <i>A. d. ravitergum</i> (circle) near Baní, Dominican Republic.

<p>Numbers reflect sample size of symptomatic lizards tested for adenovirus and the number of positive tests in parentheses.</p