Examining effects of persistent retroviral infection on fitness and pathogen susceptibility in a natural feline host

Abstract

Many animal populations carry endemic (i.e., permanently present) viruses but few studies have assessed the demographic consequences of these infections under natural conditions. We examined the effects of chronic infection with FIV Pco , a feline retrovirus, on the fitness and pathogen susceptibility of its natural host, the cougar (Puma concolor (L., 1771)), in the wild. Based on data obtained through intensive monitoring of 160 cougars from two populations, we estimated survival and different measures of host fecundity of infected and uninfected individuals. In addition, we used serological data collected from 207 cougars to test whether FIV Pco predisposes individuals to a higher probability of infection with other pathogens. We found no evidence for an overall reduction in survival due to FIV Pco when accounting for other sources of demographic variation (age, sex, and population). There was a consistent but nonsignificant trend towards poorer reproductive performance in FIV Pco -infected females. We found no serological evidence for a higher probability of secondary infections associated with FIV Pco . Overall, these results support the premise that chronic FIV Pco infection is asymptomatic in its natural cougar host, probably because of a long evolutionary association between virus and host. However, results of stochastic simulations indicate that only larger reductions in annual survival (>20%) can be excluded with confidence. Also, the possibility of a so far unrecognized cost of FIV Pco infection on cougar fecundity remains.Résumé : La plupart des populations animales portent des virus endémiques, c'est-à-dire présents en permanence, mais peu d'études ont évalué les conséquences démographiques de ces infections en conditions naturelles. Nous avons examiné les effets d'une infection chronique à FIV Pco , un rétrovirus félin, sur la fitness et la vulnérabilité aux pathogènes chez son hôte naturel, le couguar (Puma concolor (L., 1771)), en nature. D'après des données d'observation suivie de 160 couguars de deux populations, nous avons estimé la survie et diverses mesures de la fécondité de l'hôte chez des individus infectés et sains. De plus, des données sérologiques prélevées sur 207 couguars nous ont servi à vérifier si la présence de FIV Pco prédispose les individus à de plus fortes probabilités d'infection par d'autres agents pathogènes. Il n'y a pas d'indication d'une réduction globale de la survie à cause de FIV Pco , une fois qu'on a tenu compte des autres sources de variation démographique (âge, sexe, population). Il y a une tendance soutenue mais non significative d'une performance reproductive moindre chez les femelles infectées au FIV Pco . Il n'y a pas d'indication sérologique d'une probabilité plus grande d'infections secondaires associée au FIV Pco . Dans leur ensemble, ces résultats appuient la pré-misse que l'infection chronique au FIV Pco est non symptomatique chez son hôte naturel le couguar, ce qui est probablement facilité par une longue association entre le virus et son hôte au cours d...

An agent‐based movement model to assess the impact of landscape fragmentation on disease transmission

“…FIV is found in many felid species, including bobcats (Franklin et al 2007, Bevins et al 2012 and is transmitted via exchange of bodily fluids, for example through aggressive or mating encounters. The pathogen typically does not cause direct mortality or affect fitness in non-domestic felids (Biek et al 2006), and the feline host remains persistently infective (VandeWoude and Apetrei 2006). The simulated disease has no direct effect on an agent other than changing the disease state stored in the agent's disease network node, and there is no recovery/resistant stage nor a return to a susceptible state.…”

Frequent Transmission of Immunodeficiency Viruses among Bobcats and Pumas

“…The seroprevalence of these infections in natural settings ranges from nearly 100%, as, for example, among lion prides in Africa and pumas in Wyoming and Montana, to rare or absent among small wild felids of the neotropics and Asian lion prides (4,8,28,46,47). While no noticeable changes in survival rates or fecundity have been observed in populations with high seroprevalence (5,17), individual animals in captive populations have been diagnosed with an immunodeficiency-like disease (7,9; S. Kennedy-Stoskopf, L. H. Spelman, and M. Briggs, presented at the American Association of Zoo Veterinarians Annual Meeting, 1994), and others have suggested that feline immunodeficiency virus (FIV) infection of lions may have subclinical (32,39) or even overt (http://www.lionaid.org/science/results.htm) effects on animal health. Domestic cats (Felis catus) harbor a species-specific variant of feline lentivirus first isolated from a multicat household experiencing numerous fatalities associated with immune system dysfunction (31).…”

The molecular biology and evolution of feline immunodeficiency viruses of cougars

“…To determine whether, FIVpco infection affected cougar survival we estimated the monthly survival of 160 infected and uninfected animals derived from two populations (Biek et al, 2006c). Radio telemetry was used to determine if animals were alive or dead on a weekly basis, which resulted in a total of 2672 cougar-months observations.…”

“…The Akaike Information Criterion with small sample size correction (AIC C ) was used to rank models and unconditional survival estimates and their variances were calculated for each group using model averaging (Burnham and Anderson, 2002). There was no difference in survival between infected and uninfected cougars regardless of age, gender or population (Biek et al, 2006c). It is also noteworthy that similar analyses demonstrated that there was no affect of FIVple infection in African lions (Packer et al, 1999).…”

“…We also assessed the affect of FIVpco infection on fecundity by estimating the annual probability that a female would produce a litter, the average litter size, and the average number of offspring per litter surviving to independence (Biek et al, 2006c). Here the models considered FIVpco status and population affiliation and model selection criteria were similar to those used for survival analysis.…”