Airsacculitis Induced in Broilers with a Combination of Mycoplasma gallinarum and Respiratory Viruses

Abstract

Mycoplasma gallinarum was isolated from tracheas and air-sac lesions from broilers in flocks having higher than normal condemnations due to airsacculitis. A representative M. gallinarum isolant, given by aerosol or by air-sac inoculation, produced air-sac lesions in young chickens when given in combination with a vaccine combining Newcastle disease and infectious bronchitis or with a field strain of infectious bronchitis virus.

Pathogenicity ofMycoplasma imitansin mixed infection with infectious bronchitis virus in chickens

“…In the current experiment, Mim behaved similarly to this, although Kleven et al (1978) administered M. gallinarum directly into thoracic air sacs, while we administered Mim intranasally.…”

“…In several previous mixed infection experiments with Mg and viruses, isolation of the mycoplasma, but not virus was attempted (Corstvet & Sadler, 1966;Kleven et al, 1978;MacOwan et al, 1983), so comparison with our work is not possible. The lower isolation rate of IBV in the mixed infections could have been due to local inhibitory factors, such as interferon, induced by the mycoplasma.…”

“…Broilers concurrently infected with Mg, and a combined attenuated vaccine of Newcastle disease and infectious bronchitis viruses were more severely affected than those given Mg or vaccine alone (Rodriguez & Kleven, 1980). Kleven et al (1978) investigated the potential pathogenicity of Mycoplasma gallinarum by studying mixed infection with a vaccine or a ® eld strain of IBV. They found that the presence of virus, even the vaccine strain, enhanced the number of mycoplasma isolations and precipitated the inci- infections was higher than that of the group with single infection, but not signi® cantly so (P .…”

Links and interactions between mycoplasmas and viruses: past confusions and present realities

“…From epidemiological data and a number of experimental results [21,51], it clearly appears that association of respiratory viruses and M. gallisepticum (or other bacteria) results in more severe or prolonged disease for poultry, especially turkeys and broilers. Thus, viral damage of the tracheal epithelium induced by ND virus enhances the multiplication of M. gallisepticum in the trachea of experimentally infected chickens [21].…”

Genotypic heterogeneity among strains ofMycoplasma gallinarum

“…The natural host range of M. gallinarum among domesticated and wild birds is the widest of all 17 recognized avian Mycoplasma species. The species seems to be generally non-pathogenic for the chicken and turkey (Jordan, 1979), but certain strains may have the potential to induce airsacculitis in broiler chickens in association with avian infectious bronchitis virus (Kleven et al, 1978). In the chicken and turkey flocks M. gallinarum is worldwide in distribution and is one of the predominant Mycoplasma species isolated from poultry (Bencina et al, 1987b;Jordan, 1983;Poveda et al, 1990).…”