Assessment of vaccination of pigeons against paramyxovirus type 1 infection with inactivated aqueous‐suspension or oil‐emulsion vaccines

Abstract

The immune response and resistance to PMV1 challenge of pigeons vaccinated with inactivated oil-emulsion (OE) or aqueous-suspension (AS) vaccines were compared. ASa was based on NDV LaSota strain, ASb on NDV Terumo strain, OEa on NDV Poletti strain and OEb on NDV Ulster 2C strain. Groups were each vaccinated subcutaneously with one of ASa (0.2 ml), ASb (0.2 ml), OEa (0.5 ml), OEa (0.2 ml) and OEb (0.5 ml). An unvaccinated group was kept as control. The immune response measured by HI tests was the highest with the single 0.2 ml dose of ASa vaccine. The single 0.2 ml dose of OEa vaccine produced a poor HI response. Challenge with 'pigeon' PMV1 (intramuscular + intranasal/ocular) one month after vaccination resulted in the vast majority of unvaccinated pigeons excreting virus in the laryngeal secretions and the faeces and all . birds died. In comparison, virus shedding and morbidity-mortality were significantly reduced in the five challenged vaccinated groups. However, morbidity-mortality was higher in the OE groups than in the AS groups. No ASa vaccinated pigeon developed clinical signs and only one ASb vaccinated pigeon presented nervous signs. In contrast, morbidity-mortality reached 30 and 35% in the OE vaccinated groups. Only the inactivated aqueous-suspension vaccines, especially that prepared from NDV LaSota strain, gave, after one dose injection (0.2 ml), high resistance to a severe challenge with 'pigeon' PMV1.