Dna Vaccination of the American Crow (Corvus Brachyrhynchos) Provides Partial Protection Against Lethal Challenge With West Nile Virus

Abstract

; New York 1999 strain of West Nile virus (WNV) is nearly 100% fatal in the American crow (Corvus brachyrhynchos). We evaluated four WNV vaccine formulations in American crows, including intramuscular (i.m.) DNA vaccine, i.m. DNA vaccine with adjuvant, orally administered microencapsulated DNA vaccine, and i.m. killed vaccine. Neutralizing antibodies developed in approximately 80% of crows that received the DNA vaccine i.m. (with or without adjuvant), and in 44% that received the killed vaccine. However, no crows that received the oral microencapsulated DNA vaccine or the placebo developed WNV antibodies. All crows were challenged 10 wk after initial vaccination. No unvaccinated crows survived challenge, and survival rates were 44% (i.m. DNA vaccine), 60% (i.m. DNA vaccine with adjuvant), 0% (oral microencapsulated DNA vaccine), and 11% (killed vaccine). Peak viremia titers in the birds that survived were significantly lower as compared to titers in birds that died. Parenteral administration of a WNV DNA vaccine was associated with reduced mortality but did not provide sterile immunity. RESUMEN. La vacunación del cuervo Americano (Corvus brachyrhynchos) con vacuna de ADN proporciona protección parcial contra el desafío letal con el virus del Oeste del Nilo. La cepa del virus del Oeste del Nilo aislada en Nueva York en el año 1999 es casi 100% fatal en el cuervo Americano (Corvus brachyrhynchos). Evaluamos cuatro formulaciones de vacunas en cuervos Americanos, incluyendo una vacuna de ADN, una vacuna de ADN con adyuvante, ambas aplicadas por la vía intramuscular, una vacuna de ADN microencapsulada aplicada por la vía oral, y una vacuna inactivada aplicada por la vía intramuscular. Los anticuerpos neutralizantes se desarrollaron en aproximadamente el 80% de los cuervos que recibieron la vacuna de ADN por vía intramuscular, con o sin adyuvante, y en el 44% de los que recibieron la vacuna inactivada. Sin embargo, no se desarrollaron anticuerpos en los cuervos que recibieron la vacuna de ADN microencapsulada o en los controles no vacunados. Todos los cuervos fueron desafiados 10 semanas después de la vacunación inicial. Ninguno de los cuervos no vacunados sobrevivieron el desafío, y los porcentajes de sobrevivencia fueron del 44% para la vacuna de ADN, 60% para la misma vacuna con adyuvante, 0% para la vacuna de ADN microencapsulada, y 60% para la vacuna inactivada. Los títulos máximos de viremia en las aves que sobrevivieron fueron significantemente más bajos comparados con los títulos de los cuervos que murieron. La administración parenteral de la vacuna de ADN del virus del Oeste del Nilo estuvo asociada con una reducción de la mortalidad pero no proporcionó una inmunidad total. Abbreviations: ABSL-3 5 animal biosafety level-3; BA1 5 bovine albumin-1; E 5 envelope protein; i.m. 5 intramuscular; NY99 5 New York 1999 strain; PBS 5 phosphate-buffered saline; PFU 5 plaque forming units; prM 5 transmembrane protein; PRNT 5 plaque-reduction neutralization test; SLEV 5 Saint Louis encephalitis virus; WNV 5 West Nile virus

West Nile Virus Infection in Ruffed Grouse (Bonasa umbellus): Experimental Infection and Protective Effects of Vaccination

“…Vaccination has been considered in free-ranging corvids for controlling WNV outbreaks; 4 however, the logistical challenges of vaccinating free-ranging birds, including ruffed grouse, are difficult to overcome. A vaccination cohort was included in the present study because this management practice is used in some captive (breeding) grouse flocks and, in dire circumstances, may provide an option to attempt to mitigate the effects of WNV on wild bird populations.…”

Transmission dynamics and changing epidemiology of West Nile virus

“…Crows, jays and other members of the family Corvidae suffer extremely high mortality rates following WNV infection. Several studies have demonstrated 100% mortality in American crows experimentally infected with New York strains of WNV (Komar et al, 2003a;Brault et al, 2004Brault et al, , 2007Bunning et al, 2007). The overall American crow population in the USA has declined by an estimated 45% since the introduction of the virus in 1999 (LaDeau et al, 2007).…”

West Nile virus from an avian conservation perspective

“…Although most WNV vaccines are administered intramuscularly, trials involving a single‐dose oral vaccination scheme have been performed to assess the possibility of widespread vaccination of free‐ranging birds. Thus far, results have not been promising, with no evidence of seroconversion or protection against mortality (Turell et al ., ; Bunning et al ., ). Reported adverse effects of vaccination are rare and include vaccine‐site muscle inflammation in Western scrub jays (Wheeler et al ., ).…”

“…0–100%) (Nusbaum et al ., ; Johnson, S., ; Siegal‐Willott et al ., ; Okeson et al ., ; Davis et al ., ; Olsen et al ., ; Glavis et al ., ; Wheeler et al ., ). This vaccine failed to protect American crows against mortality upon WNV challenge (Bunning et al ., ) but appeared to dampen viremia and diminish pathology in Sandhill cranes Grus canadensis (Olsen et al ., ). A canarypox‐vectored vaccine failed to elicit seroconversion in Western scrub jays at 2 and 4 weeks post‐vaccination; furthermore, vaccinated scrub jays had similar viremia profiles, mortality rates and pathology as non‐vaccinated control birds (Wheeler et al ., ).…”