Characterization of West Nile Viruses Isolated from Captive American Flamingoes (Phoenicopterus ruber) in Medellin, Colombia

Abstract

Abstract. Serum samples from a total of 71 healthy captive birds belonging to 18 species were collected in July of 2008 in Medellin (Colombia) and tested for flaviviruses. Eighteen of 29 samples from American Flamingoes (Phoenicopterus ruber) were positive for West Nile virus (WNV) by reverse transcription-polymerase chain reaction. Selected positive samples were serially passaged and WNV was confirmed by immunofluorescence. Two isolates (524/08, 9835/08) were characterized in vitro and in vivo. Sequence analysis revealed WNV with 16 nucleotide substitutions resulting in six amino acid changes when compared with the NY99 strain. Colombian (COL) viruses were more closely related to Louisiana isolates from 2001. When compared with attenuated strains isolated from Texas, COL isolates differed in their plaque size and temperature sensitivity phenotype. The COL viruses were pathogenic in embryonated chicken eggs and Balb/c mice.

The Global Ecology and Epidemiology of West Nile Virus

“…Interestingly, sequences obtained from Colombian viral isolates in 2008 were most closely related to 2001 Louisiana, U.S. sequences of the NY99 genotype, suggesting that the WN02 genotype which replaced NY99 in the U.S. had not progressed southward over that time period [ 317 ].…”

Evolutionary relationships of West Nile virus detected in mosquitoes from a migratory bird zone of Colombian Caribbean

“…Serologic evidence for the natural circulation of WNV in Colombia has been observed in equids sampled from the department of Córdoba [ 7 , 8 ] and other regions from the Caribbean [ 9 – 11 ]. Despite WNV being isolated for the first time from captive flamingoes in Santa Fé Zoo (Medellín, Colombia) [ 12 ], it is not clear why WNV has not been isolated from or been the cause of detectable disease in horses or humans in Colombia. Possible explanations include: circulation of WNV in remote enzootic cycles away from human settlements, limited vector competence of mosquito species, ornitophilic blood-feeding preferences, cross-protective immunity in humans from other flaviviruses (dengue, Saint Louis encephalitis viruses), or the circulation of WNV-strains with low or attenuated virulence [ 10 – 12 ].…”

“…WNV-American strains have close relationships with three Old World isolates: IS98-ST1 (Israel - 1998), PaH001 (Tunez-1997) and goose-03 (Hungary-2003), and extensive studies have allowed detailed investigations of WNV microevolution in different areas over time and also the emergence of new genotypes [ 3 ]. In this sense, phylogenetic analysis has enabled the understanding of epidemiological patterns of emergence, dispersal routes, adaptation to new hosts/mosquitoes species, and spatio-temporal patterns of evolution [ 1 , 3 , 5 , 12 ]. Evolutionary studies are necessary to identify “drivers” of emergence, molecular evolution of virulence and associations to ecological factors that allow the establishment of this arbovirus pathogen in human populations.…”

“…2 ), but in vitro phenotypic characterization showed differences with the attenuated Texas-genotype. In fact, COL524/COL9835 has high virulence in chicken eggs and newborn/4-week-old Balb/c mice [ 12 ].

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Using the chicken embryo to assess virulence of Listeria monocytogenes and to model other microbial infections

“…Finally, legal and ethical restrictions in most countries allow experiments involving chicken embryos during early developmental stages. The chicken embryo model has previously been used to determine the infectious capacity of many different microbes, including bacteria (for example, Francisella spp., Staphylococcus aureus, Clostridium perfringens, Escherichia coli), fungi (Candida albicans, Aspergillus fumigatus), parasites (Eimeria tenella) and viruses (for example, West Nile virus, Japanese encephalitis virus) [23][24][25][26][27][28][29][30] . Herein we provide the pinpoint adjustments required for adapting the L. monocytogenes protocol to the study of the virulence capacity of other microbial pathogens using the chicken embryo model ( Table 1).…”