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Virulence and transmissibility of Mycoplasma gallisepticum

Soeripto1, K G Whithear, G S Cottew

  • 1Department of Veterinary Paraclinical Sciences, University of Melbourne, Parkville, Victoria.

Australian Veterinary Journal
|March 1, 1989
PubMed

Insights

Four Australian Mycoplasma gallisepticum strains were tested in chickens. Strains Ap3AS and 80083 showed significant virulence, causing air sac lesions and reduced egg production, especially when combined with infectious bronchitis virus (IBV).

Area of Science:

  • Avian Health
  • Veterinary Microbiology
  • Poultry Diseases

Background:

  • Mycoplasma gallisepticum (MG) is a significant avian pathogen.
  • Understanding the virulence of different MG strains is crucial for effective disease control in poultry.
  • This study investigates the pathogenicity of four Australian MG isolates.

Purpose of the Study:

  • To assess and compare the virulence of four low-passage Mycoplasma gallisepticum strains in chickens.
  • To determine the impact of these strains on air sac lesions and egg production.
  • To evaluate the effect of co-infection with infectious bronchitis virus (IBV).

Main Methods:

  • Experimental infection of chickens (broilers, layers, breeders) with four MG strains (Ap3AS, 80083, 82078, QXO).
  • Intra-abdominal (IA) and upper respiratory tract inoculation routes were used.
  • Assessment of gross lesions, egg production loss, and clinical signs, including conjunctivitis.
  • Quantification of MG in tracheal washings, particularly in co-infection models with IBV.

Main Results:

  • Strain Ap3AS and 80083 demonstrated significant pathogenicity, causing severe air sac lesions and substantial egg production loss in adult hens.
  • Strains 82078 and QXO exhibited moderate pathogenicity.
  • Intra-abdominal inoculation was more effective in eliciting lesions than upper respiratory tract administration.
  • Co-infection with IBV exacerbated clinical signs, with strain 80083 showing higher MG loads in tracheal washings than Ap3AS.

Conclusions:

  • Mycoplasma gallisepticum strains Ap3AS and 80083 are highly virulent, posing a significant threat to commercial poultry production in Australia.
  • Virulence is route-dependent, with IA inoculation being a reliable method for lesion induction.
  • Co-infection with IBV can enhance MG pathogenicity and clinical manifestations.
  • Further research into strain-specific virulence factors and host-pathogen interactions is warranted.

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