Infection and immunity in broiler chicken breeders vaccinated with a temperature-sensitive mutant of Mycoplasma gallisepticum and impact on performance of offspring

Abstract

A comparison of infection and immunity to Mycoplasma gallisepticum (MG) in broiler chicken breeders vaccinated with a temperature-sensitive mutant of MG versus nonvaccinated chickens, and the impact on the performance of their offspring was conducted. Infection and immunity in breeders were assessed by culture and enzyme-linked immunoassay, respectively. However, performance in their offspring was assessed by studying MG infection in embryos, occurrence of infection titers to MG in relation to mortality, and feed conversion in the broilers. Five out of 10 broiler chicken breeder flocks raised on the same multiple-age farm with a long history of mycoplasmosis were vaccinated intraocularly once with a temperature-sensitive MG mutant vaccine (ts-11) at an average age of 7.5 wk; another five breeder flocks were left as unvaccinated controls exposed to field MG. The average recoveries of ts-11 organisms from tracheas and infraorbital sinuses of 41-wk-old vaccinates were 88 and 84%, respectively. No field MG organisms were recovered from vaccinates between 15 and 41 wk of age. The recovery of field MG organisms from tracheas and sinuses of nonvaccinated chickens increased to an average of 100% at 41 wk of age. A significant decrease (P < 0.05) in the average percentage of MG-seroconverted breeders occurred in ts-11-vaccinated flocks in comparison with nonvaccinated, MG-infected flocks at 15, 20, 23, 29, 32, 36, and 41 wk of age. The average infection prevalence by MG in the vitelline membrane of 7-d-old embryos produced by the five unvaccinated breeder flocks peaked at 79% when their respective hatching eggs were collected at 36 wk of breeder's age. Embryos of ts-11-vaccinated flocks had zero prevalence of MG infection at all times between 29 and 57 wk of breeder's age. Seroconversion to MG (average of 17.7%) at 42 d of age was only present in sera of 10 offspring broiler flocks of the nonvaccinated breeders. However, a lack of seroconversion to MG occurred in 10, 42-d-old offspring broiler flocks of the five ts-11-vaccinated breeder flocks. This lack was associated with a lower, better average feed-conversion ratio (2.05) (P < 0.05) and a lower average mortality percentage (5.3%) (P < 0.05) in comparison with those obtained in the offspring of the five unvaccinated, MG-infected breeder flocks. The results indicate that vaccination of broiler chicken breeders with a temperature-sensitive mutant of MG prevented infection by field MG in tracheas and infraorbital sinuses of these breeders and in the vitelline membranes of their embryos. In addition, the broiler offspring of the vaccinated breeders had a better production performance.

Evaluation of the egg transmission and pathogenicity of Mycoplasma gallisepticum isolates genotyped as ts-11

“…It is recognized as a strain of low or no virulence (Whithear et al, 1990b) and has been demonstrated to provide protection against respiratory disease, egg production drops and vertical transmission associated with virulent M. gallisepticum infection (Whithear et al, 1990a;Abd-el-Motelib & Kleven, 1993;Whithear, 1996;Barbour et al, 2000).…”

“…The ts-11 vaccine strain is regarded to be of low or no virulence and has been demonstrated to provide protection against respiratory disease and egg production drops induced by virulent M. gallisepticum infection (Whithear et al, 1990a;Abd-elMotelib & Kleven, 1993;Whithear, 1996) and to reduce vertical transmission of M. gallisepticum field strains (Whithear, 1996;Barbour et al, 2000). The ts-11 vaccine's lack of virulence is not contingent on the ts + phenotype (Whithear, 1996); the genetic basis of its attenuation remains to be determined.…”

Current Status of Veterinary Vaccines

“…Temperature-sensitive-mutant vaccines have also been developed and marketed as eye drop, spray, or inhalation vaccines. These include vaccines against Mycoplasma synoviae and M. gallisepticum in chickens (Vaxsafe MS and Vaxsafe MG, respectively) (10,119) and Bordetella avium rhinotracheitis (coryza) in turkeys (Art Vax) (79).…”

IsMycoplasma synoviaeoutrunningMycoplasma gallisepticum? A viewpoint from the Netherlands

“…Inactivated M. gallisepticum vaccines tend to reduce the infection pressure on a farm after longterm use (Kleven, 1985;Whithear, 1996). The beneficial use of live vaccines results from the replacement of field strains by the vaccine strain (Whithear, 1996;Kleven et al, 1998;Barbour et al, 2000). More recent studies showed that although M. gallisepticum vaccination does not prevent colonization and horizontal transmission of the challenge strain, it significantly reduced its shedding (Feberwee et al, 2006a, b).…”