The 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.

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To better understand the potential environmental health risk presented by West Nile virus (WNV)-contaminated feces, we quantified the amount of WNV present in the feces of experimentally infected American crows (Corvus brachyrhynchos) and fish crows (Corvus ossifragus). Peak fecal titers ranged from 10(3.5) to 10(8.8) plaque-forming units (PFU)/g for 10 American crows and from 10(2.3) to 10(6.4) PFU/g for 10 fish crows. The presence of infectious WNV in bird feces indicates a potential for direct transmission of WNV. Thus, handlers of sick or dead birds should take appropriate precautions to avoid exposure to fecal material.

; 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