The invasive capacity of Mycoplasma synoviae was demonstrated. This mechanism enables mycoplasma dissemination and avoiding to host immune defense. Using gentimicin invasion assay and immunostainig relative invasive frequency (RIF) was demonstrated for four M. synoviae strains in three chicken cell types: erythrocytes (CER), embryonic fibroblasts (CEC-32) and primary cell culture of chicken chondrocytes (CCH). Type strain WVU 1853 was more invasive for CCH and CEC-32 cells and similarly invasive for CCH as M. gallisepticum Rlow. Field strains of M. synoviae were even less invasive for CCH.
Neuraminidase NanH, synthesized by M. synoviae, is linked to invasiveness and pathology in infected poultry. In M. synoviae strains that lack the neuraminidase activity we found the mutation in nanH gene that prevent the neuraminidase activity. We demonstrated that NanH from M. synoviae cleave the syalic acid from chicken immunoglobulins IgG (IgY) i.e. sia ? (2-6) gal from the heavy chain (CH2 domain). NanH also cleaves the syalic acid from glycoproteins in chicken tracheal mucus. We demonstrated the same neuraminidase activity and cleavage for the LaSotta virus.