Mesomycoplasma ovipneumoniae from goats with respiratory infection: pathogenic characteristics, population structure, and genomic features

Application of multi-omics technology in pathogen identification and resistance gene screening of sheep pneumonia

BACKGROUND

Pneumonia constitutes a major health challenge in sheep, severely compromising growth rates and overall productivity, and resulting in considerable economic losses to the sheep industry. To address this issue, the development of disease-resistant breeding programs based on the identification of genetic markers associated with pneumonia susceptibility is of critical importance. This study investigated a sheep population on a farm where pneumonia was endemic. The purpose was to use multi-omics methods to rapidly identify the principal pathogens responsible for pneumonia outbreaks, and to screen for genetic loci and key genes related to pneumonia resistance, thereby providing a scientific basis for the implementation of targeted breeding strategies for pneumonia resistance.

RESULTS

Here, we assessed the impact of pneumonia on sheep growth by evaluating the pneumonia phenotypes of 912 sheep. High-throughput transcriptome sequencing of 40 lungs was conducted to obtain exogenous RNA fragments for microbial sequence alignment. Additionally, 16S rRNA sequencing was performed on lung tissues from 10 healthy and 10 diseased sheep to identify biomarkers associated with phenotypic differences. Mycoplasma ovipneumoniae was identified as the primary pneumonia pathogen, and its presence was further validated by load quantification and immunohistochemical analysis. Integration of genome-wide association study (GWAS) data from 266 lung pathological scores with transcriptome-based differentially expressed genes analysis enabled the identification of five single nucleotide polymorphisms (SNPs) and three potential candidate genes associated with Mycoplasma pneumonia. Subsequent genotyping and phenotype association analyses confirmed the significance of two SNPs and established a strong association between the FOXF1 gene and resistance to Mycoplasma pneumonia.

CONCLUSIONS

High-throughput sequencing technologies have enabled the rapid and accurate identification of the causative pathogen of sheep pneumonia. By integrating multi-omics data, two genomic loci significantly associated with Mycoplasma pneumonia were screened, as well as an anti-Mycoplasma pneumonia key gene, FOXF1.

Mycoplasma ovipneumoniae identified as the main aetiological agent of respiratory disease in goats from a case-control study in Savannakhet province of Lao PDR

Clinical signs of respiratory disease are common in Lao goats. To identify the causative agents involved in this clinical syndrome, a matched case-control study was conducted across 70 smallholder goat holdings in Savannakhet province. Fifty paired nasal swab samples were collected from goats with respiratory signs (cases) and unaffected (control) goats from 27 goat holdings. The majority of cases (84 %) were from goats < 12 months of age. Samples were tested using quantitative PCR assays targeting possible pathogens causing respiratory disease. Mycoplasma ovipneumoniae, the cause of atypical pneumonia, was prevalent in both case (94 %) and control (76 %) groups and was identified as the principal causative agent based on odds ratio of presence (4.9) and a significantly higher pathogen load in case goats. Prolonged close contact between goats during confinement in often poorly constructed goat houses, likely facilitates transmission and progression from carrier to clinical status under the Lao goat production system. Mannheimia haemolytica was detected in 60 % of case and 52 % of control samples with no significant difference in pathogen load, while Pasteurella multocida was detected in only 2 % of control samples indicating no major role in causation for these pathogens. Mycoplasma capricolum subsp. capripneumoniae, respiratory syncytial virus and bovine parainfluenza 3 virus were not detected in any samples. Phylogenetic analysis showed no genetic variation of M. ovipneumoniae in the study samples and close similarity to recent isolates from China, US and Turkey. Improved housing conditions may be helpful in controlling atypical pneumonia in Lao goats and antibiotic treatment of goats with severe signs of respiratory disease was found to be effective.

Isolation and Characterization of Mycoplasma ovipneumoniae Infecting Goats with Pneumonia in Anhui Province, China

Mycoplasma ovipneumoniae (M. ovipneumoniae) causes a fatal infection in goats, leading to significant economic losses in the small-ruminant industry worldwide. The present study aimed to characterize the strains of M. ovipneumoniae infecting goats with pneumonia in Anhui Province, China. From November 2021 to January 2023, among 20 flocks, a total of 1320 samples (600 samples of unvaccinated blood, 400 nasal swabs, 200 samples of pleural fluid, and 120 samples of lung tissue) were obtained from goats with typical signs of pneumonia, such as a low growth rate, appetite suppression, increased temperature, discharge from the nose, and a cough. Necropsied goats showed increased pleural fluid, fibrinous pleuropneumonia, and attached localized pleural adhesions. M. ovipneumoniae isolated from the samples were subjected to an indirect hemagglutination test (IHA), PCR amplicon sequencing, phylogenetic analysis, and biochemical identification tests. The overall positivity rate of M. ovipneumoniae was 27.50%. Mycoplasmas were obtained from 80 (20.0%) nasal swabs, 21 (10.5%) pleural fluid samples, and 15 (12.5%) lung samples. PCR amplicon (288 bp) sequencing identified eight strains of M. ovipneumoniae. In a phylogenetic tree, the isolated strains were homologous to the standard strain M. ovipneumoniae Y-98 and most similar to M. ovipneumoniae FJ-SM. Local strains of M. ovipneumoniae were isolated from goats in Anhui province. The identified genomic features and population structure will promote further study of M. ovipneumoniae pathogenesis and could form the basis for vaccine and therapy development.