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Pathogenicity of Mycoplasma synoviae in chicken embryos
S B Lockaby1, F J Hoerr, S H Kleven
1Department of Veterinary Pathobiology, Auburn University, AL 36849, USA.
Abstract:
Pathogenicity of Mycoplasma synoviae (MS) was examined in specific-pathogen-free (SPF) white leghorn chicken embryos. Six isolates of MS were inoculated into 7-day embryos via the yolk sac. Isolates were evaluated for gross and microscopic lesions through 19 days' incubation and for embryo lethality through 20 days' incubation. Isolates in decreasing order of lethality, from lowest to highest 50% embryo lethal dose, were WVU 1853, K1968, K1858, FMT, 92D8034, and F10-2AS. Embryo lethality was consistent with lesion incidence and severity. Embryo lethality did not correlate with previous results regarding pathogenicity of these same six isolates in SPF broiler chickens.
Insights
This study assessed Mycoplasma synoviae (MS) pathogenicity in chicken embryos, finding varying lethality among isolates. Embryo lethality correlated with lesions but not with prior broiler chicken pathogenicity results.
Area of Science:
- Veterinary Virology
- Avian Pathology
- Microbiology
Background:
- Mycoplasma synoviae (MS) is an important avian pathogen.
- Understanding MS pathogenicity in early life stages is crucial for disease control.
- Previous studies have assessed MS pathogenicity in broiler chickens.
Purpose of the Study:
- To evaluate the pathogenicity of six Mycoplasma synoviae isolates in specific-pathogen-free (SPF) chicken embryos.
- To compare embryo lethality and lesion development among different MS isolates.
- To determine if embryo pathogenicity correlates with previously observed pathogenicity in SPF broiler chickens.
Main Methods:
- Six Mycoplasma synoviae isolates were inoculated into the yolk sacs of 7-day-old SPF white leghorn chicken embryos.
- Embryos were monitored for gross and microscopic lesions up to 19 days of incubation.
- Embryo lethality was assessed up to 20 days of incubation, determining the 50% embryo lethal dose (ELD50) for each isolate.
Main Results:
- Significant variation in embryo lethality was observed among the six MS isolates.
- Isolates WVU 1853, K1968, K1858, FMT, 92D8034, and F10-2AS showed a progressive increase in lethality (lowest to highest ELD50).
- Embryo lethality correlated positively with the incidence and severity of observed lesions. However, embryo pathogenicity did not correlate with previous pathogenicity findings in SPF broiler chickens.
Conclusions:
- Mycoplasma synoviae exhibits differential pathogenicity in chicken embryos.
- Chicken embryos serve as a viable model for assessing MS pathogenicity, with lethality linked to lesion development.
- Pathogenicity in chicken embryos does not directly predict pathogenicity in broiler chickens, suggesting stage- or host-specific virulence.