Genomic regions associated withMycoplasma ovipneumoniaepresence in nasal secretions of domestic sheep

Abstract

Mycoplasma ovipneumoniae contributes to polymicrobial pneumonia in domestic sheep. Elucidation of host genetic components to M. ovipneumoniae nasal detection would have the potential to reduce the incidence of pneumonia. Nasal mucosal secretions were collected from 647 sheep from a large US sheep flock. Ewes of three breeds (Polypay n=222, Rambouillet n=321, and Suffolk n=104) ranging in age from one to seven years, were sampled at three different times of the production cycle (February, April, and September/October) over four years (2015 to 2018). The presence and quantity of M. ovipneumoniae was determined using a species-specific qPCR with 3 to 10 sampling times per sheep. Breed (P<0.001), age (P<0.024), sampling time (P<0.001), and year (P<0.001) of collection affected log 10 transformed M. ovipneumoniae DNA copy number, where Rambouillet had the lowest (P<0.0001) compared with both Polypay and Suffolk demonstrating a possible genetic component to detection. Samples from yearlings, April, and 2018 had the highest (P<0.046) detected DNA copy number mean. Sheep genomic DNA was genotyped with the Illumina OvineHD BeadChip. Principal component analysis identified most of the variation in the dataset was associated with breed. Therefore, genome wide association analysis was conducted with a mixed model (EMMAX), with principle components 1 to 6 as fixed and a kinship matrix as random effects. Genome-wide significant (P<9x10 -8 ) SNPs were identified on chromosomes 6 and 7 in the all-breed analysis. Individual breed analysis had genome-wide significant (P<9x10 -8 ) SNPs on chromosomes 3, 4, 7, 9, 10, 15, 17, and 22. Annotated genes near these SNPs are part of immune ( ANAPC7 , CUL5 , TMEM229B , PTPN13 ), gene translation ( PIWIL4 ), and chromatin organization ( KDM2B ) pathways. Immune genes are expected to have increased expression when leukocytes encounter M. ovipneumoniae which would lead to chromatin reorganization. Work is underway to narrow the range of these associated regions to identify the underlying causal mutations.

Whole genome sequencing reveals a complex introgression history and the basis of adaptation to subarctic climate in wild sheep

“…The introgressed segments between the snow sheep lineage and argali contain genes mainly involved in immune response, adipogenesis and adaptation (Figure 5a; Table ). For instance, the PKN2 gene has been associated with responses to viral respiratory disorders in the domestic pig and Mycoplasma ovipneumoniae infection in sheep (Dekkers et al, 2017; Mousel et al, 2021). Indeed, the adaptive introgression of immune‐related genes has been hypothesized in other mammalian species, including humans, Iberian hares and alpine ibex (Deschamps et al, 2016; Grossen et al, 2014; Holloway et al, 2011).…”

Evolution of the sheep industry and genetic research in the United States: opportunities for convergence in the twenty‐first century

“…More recently two research groups have been part of the effort to identify genomic regions affiliated with Mycoplasma ovipneumoniae (Mousel et al . 2021 ) and the degenerative condition ovine Johne’s disease (Y. Yaman, in review). Genetic markers for scrapie have resulted in reduced susceptibility using associated variants of PRNP at codons 136, 141, 154 and 171 (Hunter et al .…”

“…Recently, Mousel et al . ( 2021 ) has presented research that could aid in solving the problem of disease transmission between wild and domestic sheep.…”

“…Notably, Heaton et al (2012) first described variants within TMEM154 associated with reduced susceptibility to lentivirus and Mousel et al (2015) identified significant SNP in SLC2Ap and near NLN affiliated with entropion. More recently two research groups have been part of the effort to identify genomic regions affiliated with Mycoplasma ovipneumoniae (Mousel et al 2021) and the degenerative condition ovine Johne's disease (Y. Yaman, in review). Genetic markers for scrapie have resulted in reduced susceptibility using associated variants of PRNP at codons 136, 141, 154 and 171 (Hunter et al 1994;Westaway et al 1994;Belt et al 1995;Moum et al 2005).…”

“…There is strong evidence that the immunopathologic response to M. ovipneumoniae differs between domestic and wild sheep (Grossman et al 2019), often resulting in more detrimental effects of the pathogen to wild sheep. Recently, Mousel et al (2021) has presented research that could aid in solving the problem of disease transmission between wild and domestic sheep. With production scenarios in the USA evolving, producer priorities for animal selection are also becoming more diverse.…”