Investigation on mycoplasma populations in pneumonic dairy lamb lungs using a DNA microarray assay

Respiratory disease in sheep is accountable for considerable financial losses worldwide. While the most noticeable cause of pneumonic pasteurellosis is Mannheimia haemolytica, the role of mycoplasmas, particularly Mycoplasma ovipneumoniae, have been overlooked. Further, “atypical” Mycoplasma species occasionally associated with respiratory disease have been detected from sheep lungs worldwide. The aim of this work was to carry out an epidemiological survey on mycoplasma population in pneumonic lungs of very young dairy lambs in relation with the detection of other respiratory pathogens. Genomic DNA was extracted from 115 pneumonic lungs of one-month old dairy lambs. The DNA was then tested using a DNA Microarray for Mycoplasma species and three PCR assays for M. haemolytica, Parainfluenza-3 virus (PI3V) and Respiratory Syncytial Virus (RSV) respectively. 25 animals tested positive for M. ovipneumoniae (21.7%), six of which tested positive also for M. arginini (5.2%). No atypical mycoplasma species was detected with the DNA microarray assay. 50 animals tested PCR positive for M. haemolytica (43.5%), 21 of which tested positive also for M. ovipneumoniae (84%). All the samples tested PCR negative for PI3V and RSV. The results obtained from this epidemiological investigation broaden the knowledge about the prevalence of Mycoplasma species in the lungs of very young dairy lambs.