West Nile Virus Detection in the Organs of Naturally Infected Blue Jays (Cyanocitta Cristata)

Abstract

Blue jays (Cyanocitta cristata) are an effective indicator species for West Nile virus (WNV) and may be regionally important in surveillance efforts. The sites of WNV replication and sensitivity of virus detection techniques are undefined for blue jays. The objectives of this study were to describe the gross and microscopic pathology associated with natural WNV infection in blue jays, as well as determine the most appropriate tissues to be used for virus isolation, reverse transcription-nested polymerase chain reaction, and immunohistochemistry (IHC) techniques. Blue jays were collected in Georgia, USA, between May and September 2001. Initial screening by virus isolation indicated that 36 of 59 blue jays chosen for evaluation were WNV positive. From this group, 20 positive and five negative birds were chosen to compare virus detection techniques. Six positive and five negative birds were selected for histopathology examination. Splenomegaly and poor body condition were the most consistent gross findings among positive birds. The most consistent histopathologic findings in the tissues of WNV-positive blue jays were mononuclear leukocytosis and epicarditis/myocarditis. Brain, heart, and lung had the highest viral titers, and WNV antigen was most often detected by IHC in heart, kidney, liver, and lung. Reverse transcription-nested polymerase chain reaction proved to be the most sensitive diagnostic test applied in this study irrespective of the tissue type. Brain tissue could be used effectively for both virus isolation and RT-nPCR, and this tissue is simple to remove and process. The success of IHC is highly dependent on tissue selection, and the use of multiple tissues including heart, kidney, liver, or lung is recommended.

Prevalence and Pathology of West Nile Virus in Naturally Infected House Sparrows, Western Nebraska, 2008

“…Interestingly, although there is typically little pathology in corvids infected with WNV, virus is frequently isolated from multiple tissues. 48,49 This may reflect species differences in susceptibility to the virus and a rapid course of disease leading to death in crows and jays. The tissue pathology shown in the two field-collected house sparrows indicates that these nestlings likely maintained high viremic titers in blood, perhaps for several days before death, and presumably lived longer after infection than do corvids.…”

Glycosylation of the West Nile Virus Envelope Protein Increases In Vivo and In Vitro Viral Multiplication in Birds

“…These histopathological changes were also seen in birds that had been naturally infected with WN virus. 21 Efficient viral propagation both in avian and mosquito hosts is an important determinant of active viral circulation in the natural transmission cycle. We tested the viremic levels of LP and SP variants in chicks to reveal the effect of glycosylation of the WN virus E protein on the magnitude of viremic levels.…”

Morphological Description of American Crow, <em>Corvus brachyrhynchos</em>, Populations in Southern Quebec

“…It has been observed that some bird species of the Passeriformes order present a lower body condition after WNV infection (Steele et al 2000;Gibbs et al 2005). As of yet, this observation was rare for the American Crow (Dallaire, A.D., Centre québécois pour la santé des animaux sauvages, 2007, personal communication).…”