Immunogenicity ofRiemerella anatipestiferbroth culture bacterin and cell‐free culture filtrate in ducks

Abstract

Strains belonging to Riemerella anatipestifer serotype 1 are responsible for most of the major disease outbreaks caused by this organism in ducks in Thailand. Therefore, the immunogenicity induced by a broth culture bacterin prepared from a local strain (1081) of this serotype was studied in ducks and a protective index (PI) was derived. The inactivated vaccine contained the equivalent of 5 X 10(9) colony-forming units of bacteria per 0.5-ml dose. A single subcutaneous inoculation of the broth culture bacterin in 2-week-old Khaki Campbell ducklings gave adequate protection (PI = 88) against challenge with the homologous strain 7 days after vaccination, while the highest protection (PI = 95.6) was obtained 2 weeks after vaccination. The duration of immunity was at least 6 months. Inoculation of the vaccine at both 1 and 5 weeks of age gave the greatest protection. The vaccine was found to be safe in one-week-old ducklings and it also gave significant protection (PI values from 66.7 to 100) against challenge with virulent strains of the homologous serotype. The immunogenicity of broth culture bacterin prepared from local strains of various serotypes was also studied. Strains of serotypes 1, 6, 11, 14 and 19 gave no significant protection against challenge with strains of heterologous serotypes. Concentrated cell-free culture filtrates prepared from strain 1081 of serotype 1 and strain 328 of serotype 19 induced highly significant protection against homologous challenge (P < 0.01), but cross-protection between the two strains was not significant.

Evaluation of different diagnostic tools for the detection and identification of Riemerella anatipestifer

“…To date, 21 RA serotypes have been classified (Bisgaard, 1982;Sandhu & Leister, 1991;Loh et al, 1992;Pathanasophon et al, 1995Pathanasophon et al, , 2002 and several serologically unclassified strains have been reported, which may further increase the number of serotypes in the near future (Kö hler et al, 1997;Metzner et al, 2008). Cross-protection between the different serotypes is poor (Sandhu, 1979(Sandhu, , 1991Pathanasophon et al, 1996). Thus identification of the predominant RA serotypes circulating in a certain area is necessary for the choice of appropriate RA vaccines.…”

Identification and Characterization of CAMP Cohemolysin as a Potential Virulence Factor of Riemerella anatipestifer

“…An OmpA protein was characterized for its possible use in serodetection of R. anatipestifer infection (28). Inactivated bacterins and live vaccines have successfully conferred protection against homologous strains or serotypes of R. anatipestifer but were unable to protect against heterologous serotype exposure (20,22).…”

SURVEY OF ARIEMERELLA ANATIPESTIFEROUTBREAK IN SOUTHERN TAIWAN DUCK FARMS

“…3,20,21 RAspeci¯c OmpA has also been proposed as an identi¯ca-tion target. 5,14 Our study performed PCR ampli¯cation for both 16S rRNA and OmpA genes, with 15 out of 27 isolates found to be positive for both genes. In terms of PCR products, while the 16S rRNA PCR yielded clear single bands, some OmpA PCR products included double bands (e.g.…”

“…13 Inactivated bacterins and live vaccines have successfully conferred protection against homologous strains of RA, but were unable to protect against heterologous serotype exposure. 14,15 An important challenge for veterinary vaccines is to improve cross-serotype protection of RA infection.…”