Molecular Typing of Indian Mycoplasma synoviae Isolates

Mycoplasma synoviae is an economically significant pathogen in poultry with reported increased prevalence and virulence in recent years. The pathogen causes subclinical upper respiratory tract infection, air sacculitis and infectious synovitis.

This study aimed to characterize the field isolates of M. synoviae, from healthy and diseased birds of 13 poultry flocks of five states of India by DNA sequence analysis of the conserved 52 region of variable lipoprotein and haemagglutinin (vlhA) gene.

Phylogenetic analysis revealed 7 sequence types. Single sequence type was found in three major states for commercial poultry production, which could be due to interstate transport of birds or chicks. Typing based on nucleotide insertion/deletion in the proline-rich repeat (PRR) region and the nucleotide polymorphisms of the RIII region of the 52 region of the vlhA identified field isolates as Type C (n=8), E (n=6) and L (n=5). Subtypes identified were C1 (n=3) and C3 (n=1) and others were novel. Most of the isolates were from birds having respiratory lesions or symptoms. Synovitis cases were very rare and the isolate from synovitis was found to be of subtype C3. Further, the presence of multiple types (C1, E and L) was found in one farm even though most of the farms were affected by only single type. Molecular typing of Indian M. synoviae isolateswas conducted for the first time to map the diversity among different Indian isolates from different regions and from different clinical conditions.