ABSTRACT
Mycoplasma gallisepticum (MG) can cause respiratory disease in chickens and result in serious economic losses in the chicken industry. The use of live vaccines has been a favorable option for the control of MG infection in multi-age commercial layers and broiler breeders. There are three live vaccines, including ts-11, 6/85, and F strain, that have been commonly used in various parts of the world, including South Korea. The definitive diagnosis of the infection, therefore, requires the differentiation of wild-type field strains of MG from the vaccine strains used. Thus, we aimed to develop a novel multiplex PCR assay to discriminate between vaccine strains (ts-11, 6/85, and F strain) and wild-type field strains of MG isolated from infected chickens. We designed four novel primer sets that are each specific to MG species, ts-11, 6/85, and F strain. The multiplex PCR assay using the primer sets differentially identified wild-type and vaccine strains of MG but did not detect other avian bacteria. The detection limit of this assay was 250 fg/µL of genomic DNA of each strain tested. In addition, this assay was applied to 36 MG strains isolated from chickens over the past 20 years in South Korea. As a result, the assay identified 22 wild-type strains and 14 vaccine strains. Consequently, the novel multiplex PCR assay can discriminate between vaccine and wild-type field strains of MG and could be a valuable tool for the diagnosis of MG infection in MG-vaccinated chicken flocks.
ABSTRACT
This study evaluated the prevalence of Eimeria species, particularly E bovis, E zuernii and E auburnensis that are pathogenic to cattle, in faecal samples collected from cattle with diarrhoea reared in the Republic of Korea by using microscopy and PCR. In addition, the prevalence of Eimeria species was analysed according to age, type of cattle, region, season and nature of diarrhoea. Overall, Eimeria species were identified in 279 of the 1261 (22.1 per cent) faecal samples through microscopy, and statistical analysis revealed a lower prevalence in calves aged than three weeks or less and higher prevalence in cattle with haemorrhagic diarrhoea. Of the 279 microscopy-positive samples, E bovis, E zuernii and E auburnensis were identified in 100 (7.9 per cent), 83 (6.6 per cent) and 27 (2.1 per cent) faecal samples, respectively, by using PCR. To the authors' knowledge, this study is the first to apply PCR for epizootiology of bovine coccidiosis.
