Background: Mycoplasma bovis causes various diseases such as bronchopneumonia, otitis media, arthritis, and mastitis in cattle. M. bovis is often isolated from the deep pharynges of healthy cattle and is generally considered not to cause clinical symptoms while in the upper respiratory tract. In mycoplasma infections, adhesion to the host cells is a crucial step. In recent years, five new adhesins, NOX, α-enolase, TrmFO, P27, and VpmaX, have been reported in M. bovis strains from pneumonia cases. However, the presence of these adhesins in wild isolates has not been established.
Aim: This study aimed to investigate the presence of these adhesin genes in wild isolates isolated from cattle nasal cavities and lesion sites (pneumonia, otitis media, arthritis, and mastitis) in various regions in Japan and clarify the relationship between adhesion and the symptoms caused by M. bovis infection.
Methods: A total of 141 M. bovis wild isolates isolated from nasal cavities (healthy or sick cattle), lungs with pneumonia, ears with otitis media, joint fluids of arthritic animals, and milk of mastitic animals. M. bovis type strain PG45 was also used. Specific polymerase chain reaction reactions were performed to detect nox, α-enolase, trmFO, P27, and vpmaX, which are adhesins of M. bovis.
Results: This study reports 139 M. bovis wild isolates were positive for nox, α-enolase, trmFO, P27, and vpmaX, while two isolates each lacked α-enolase or P27 genes. M. bovis PG45 also had all five adherens genes.
Conclusion: Almost all M. bovis wild isolates possessed all nox, α-enolase, trmFO, P27, and vpmaX genes regardless of the lesion site or region of origin. This means no relationship was found between the presence of the five adhesins and lesion sites in M. bovis and M. bovis isolated from the nasal cavities of asymptomatic cattle have the same numbers and types of adhesins as isolates from symptomatic lesion sites (pneumonia, otitis media, arthritis, and mastitis). This suggests that not only M. bovis isolates from pulmonary lesions, but also M. bovis existing in the nasal cavity has the potential to causes symptoms in the host.
Key words: adhesin, cattle, Mycoplasma bovis