Vaccination of One-Day-Old Broiler Chicks Against Infectious Coryza

Abstract

In order to evaluate the protection conferred by an experimental inactivated vaccine against infectious coryza, three challenge trials were undertaken using 112 1-day-old broilers. The vaccine "Hepa Inmuno NC" included bacterial antigens of Avibacterium paragallinarum (serogroups A, B, variant B, and C) as well as antigens of Newcastle virus and hepatitis virus. Fifty-six broiler chicks were vaccinated at the first day of life at the hatchery while another 56 chicks were left unvaccinated. Three infection trials were conducted simultaneously using each of the three serogroups A, B, or C of Av. paragallinarum. In each trial, 17 vaccinated and 17 unvaccinated broilers were used. Challenge was performed at day 31 of life by injection, into the left infraorbital sinus, of approximately 1 x 10(5) colony forming units of the corresponding Av. paragallinarum strain. Clinical signs were recorded on day 2 postchallenge. All broilers were euthanatized and both infraorbital sinuses were bacteriologically examined for the presence of Av. paragallinarum on day 5 postchallenge. In comparison with the unvaccinated broilers, the vaccine significantly reduced the number of broilers with clinical signs after challenge with serogroup B, and significantly fewer vaccinated broilers were positive for the presence of Av. paragallinarum after challenge with serogroup C. On the other hand, no significant protection was observed when broilers were challenged with Av. paragallinarum from serogroup A. Despite the high infection rates in vaccinated chicks after an experimental infection with Av. paragallinarum, it was possible to reduce colonization of Av. paragallinarum (serogroup B) and clinical signs (serogroup C) in broiler chicks by vaccination at the first day of life. Further cross-protection trials should be done, including other Av. paragallinarum strains in the vaccine, especially those from serogroup A.

Pathogenicity of Avibacterium paragallinarum Strains from Peru and the Selection of Candidate Strains for an Inactivated Vaccine

“…As the pathogenicity of Av. paragallinarum might be altered upon long conservation and an undefined number of passages in artificial culture media, all strains were passaged in live birds, re-isolated, and kept with a standardized number of subcultures [ 11 , 14 ]. This way, all inoculation trials were performed under the same conditions.…”

“…Later, inoculation studies were performed comparing their capacity to cause clinical signs (Trials 1 and 2) and to spread to non-infected birds (Trial 2). The use of clinical signs score for pathogenicity studies was used by other authors, although criteria may vary, it is a good way to describe the course of infection and its severity [ 14 , 44 , 57 , 58 , 64 , 65 , 66 , 67 ]. The results of clinical signs scores, bacteriology, and deaths from Trials 1, 2, and 3 are available in Table 1 and in Supplementary Tables S2–S5 .…”

“…Usually, clinical signs and reduction of egg production will disappear within 20 days while complicated cases may last up to two months [ 11 ]. On the other hand, infectious coryza has also been reported in broilers [ 8 , 12 , 13 , 14 , 15 ] usually associated with other bacterial or viral agents [ 9 ]. When complicated with other agents, arthritis and septicaemia have also been reported [ 8 , 12 , 16 , 17 ] and there is a specific description of how the coinfection with Fowl Adenovirus increased mortality in an experimental inoculation with serogroup A field strain of Av.…”

Development and Validation of PCR Diagnostic Assays for Detection of Avibacterium paragallinarum and Ornithobacterium rhinotracheale

“…In different countries, different serogroups and serotypes of the pathogen are predominant [ 1 , 2 , 3 , 4 ]. Infectious coryza of chickens is common in countries with developed aviculture, including Russia [ 5 , 6 , 7 ]; it leads to a slowdown in the growth rate of broilers and a decrease in the egg production of chickens [ 8 ]. Chickens and turkeys of all ages are susceptible to infectious coryza, especially chickens older than 4 weeks.…”