Prevalence and Genetic Diversity of Avipoxvirus in House Sparrows in Spain

Abstract

Avipoxvirus (APV) is a fairly common virus affecting birds that causes morbidity and mortality in wild and captive birds. We studied the prevalence of pox-like lesions and genetic diversity of APV in house sparrows (Passer domesticus) in natural, agricultural and urban areas in southern Spain in 2013 and 2014 and in central Spain for 8 months (2012–2013). Overall, 3.2% of 2,341 house sparrows visually examined in southern Spain had cutaneous lesions consistent with avian pox. A similar prevalence (3%) was found in 338 birds from central Spain. Prevalence was higher in hatch-year birds than in adults. We did not detect any clear spatial or temporal patterns of APV distribution. Molecular analyses of poxvirus-like lesions revealed that 63% of the samples were positive. Molecular and phylogenetic analyses of 29 DNA sequences from the fpv167 gene, detected two strains belonging to the canarypox clade (subclades B1 and B2) previously found in Spain. One of them appears predominant in Iberia and North Africa and shares 70% similarity to fowlpox and canarypox virus. This APV strain has been identified in a limited number of species in the Iberian Peninsula, Morocco and Hungary. The second one has a global distribution and has been found in numerous wild bird species around the world. To our knowledge, this represents the largest study of avian poxvirus disease in the broadly distributed house sparrow and strongly supports the findings that Avipox prevalence in this species in South and central Spain is moderate and the genetic diversity low.

A Review on the Prevalence of Poxvirus Disease in Free-Living and Captive Wild Birds

“…Several surveys have been carried out in house sparrows (Passer domesticus), permitting the comparison of prevalences of APV in the same species in different ecosystems and regions. Van Riper et al [30] found prevalences of 2.5% and 4.9% of active and inactive avian pox lesions in 81 house sparrows captured in Hawaii (albeit a limited sample size) and similar prevalences of 3.1% were reported in an extensive sample size (2729) in Spain [46]. In contrast, Smits et al [48] did not report any clinical signs of infection in Spanish sparrows (P. hispanolensis) in the Canary Islands (n = 128).…”

“…Age and immune function are reported to be important factors explaining withinspecies differences in APV prevalence. In nearly all studies, avipox lesions are significantly more frequent in juveniles than in adults [40,[44][45][46][47]-this is anticipated, as first-year birds will not have acquired specific immunity to APV infection. Le Loc'h et al [41] showed that this pattern was true only for houbara bustards in Morocco but not in the United Arab Emirates, where pox infection affected juveniles and adults alike.…”

“…A 7-year study in Trinidad tested more than 9000 individuals of tropical birds [52]. There are also a few studies with sample sizes in the range of 2000-6000 individuals, which have been used to explore APV infection in falcons, quails, great tits, house sparrows, finches or mockingbirds in the UAE/Kuwait, USA, the UK, Spain and Galapagos [15,30,39,46,51,53,54].…”

Optimized CRISPR tools and site-directed transgenesis towards gene drive development in Culex quinquefasciatus mosquitoes

“…Its ability to hybridize with other species makes it adaptable to new environments 9 , making this mosquito a challenging vector to control. In addition, Culex quinquefasciatus is the primary vector for avian malaria and avian pox, posing existential threats to island avifauna 10 – 12 . As an example, the invasive Culex quinquefasciatus in Hawai’i has contributed to the extinction of several Honeycreeper species and continues to threaten other susceptible species on the islands 13 , 14 .…”

TaqMan quantitative real-time PCR for detecting Avipoxvirus DNA in various sample types from hummingbirds

“…Conventional PCR has been used to detect avian pox in the past [2,4] as well as to determine prevalence and genetic diversity of avian pox [27,28]; however, there are still limitations. In analyses using solely conventional PCR, parasite or viral load is difficult to determine [29] and as it relies on downstream visualization, products are handled more than once thus increasing the risk of viral contamination [30].…”