Clonality of Mycoplasma hyopneumoniae in swine farms from Brazil

Exploring the Genetic Diversity of Mycoplasma hyopneumoniae in Pigs with Pneumonia and Pleurisy at Slaughter

Mycoplasma (M.) hyopneumoniae is the key pathogen of the porcine respiratory disease complex (PRDC) and contributes to pleurisy in pigs. Due to its limited metabolism and laborious cultivation, molecular tools are useful for diagnosis. This study investigated the genetic diversity of M. hyopneumoniae in slaughter pigs with pneumonia and pleurisy, and it assessed co-infections by Pasteurella multocida type A (PM), Actinobacillus pleuropneumoniae (APP), and swine influenza virus A (sIVA). Lungs (n = 70) with different pleurisy scores and lesions compatible with M. hyopneumoniae infection were collected for convenience. Macroscopic and microscopic evaluations were performed. M. hyopneumoniae was detected using qPCR, and MLST was used for genetic characterization. Co-infections with PM and APP were also evaluated by qPCR, while the immunohistochemistry assessed sIVA infection. All lungs were positive for M. hyopneumoniae. Histopathology confirmed M. hyopneumoniae-associated lesions. MLST characterization was possible in 25 lungs and revealed 10 distinct allelic profiles, with none matching known sequence types in the public database. Co-infections were detected in 40% of the samples with APP and 32% with PM, with 12% showing both pathogens and 52% of the samples presenting microscopic lesions compatible with sIVA infection. The diverse genetic profiles found underscore the need for research on isolation and potential pathogenic variations.

Molecular detection of respiratory coinfections in pig herds with enzootic pneumonia: a survey in Brazil

Mycoplasma hyopneumoniae is the primary etiologic agent of swine enzootic pneumonia (EP), in which the immune response is reduced, making pigs susceptible to secondary infections. We surveyed commercial pig herds in Brazil for viral and bacterial respiratory coinfections that could complicate EP. Over a 2-y period (2015-2016), we found that 854 of 2,206 pigs (38.7%) were positive for M. hyopneumoniae in herds from various production systems in 3 Brazilian regions (Central-West, Southeast, South). We collected samples of 321 lungs positive for M. hyopneumoniae from 169 farms to also screen for Pasteurella multocida, Actinobacillus pleuropneumoniae, Glaesserella parasuis, influenza A virus (IAV), and porcine circovirus 2 (PCV2) by real-time PCR. The prevalence of pathogens found in addition to M. hyopneumoniae varied: P. multocida (141; 43.9%), G. parasuis (71; 22.1%), PCV2 (50; 15.6%), IAV (23; 7.2%), and A. pleuropneumoniae (18; 5.6%). G. parasuis was more frequent in farrowing or nursery herds (48.7%) than in breeding and fattening herds (10% and 18.6%, respectively; p < 0.01); A. pleuropneumoniae was found only in herds on farrow-to-finish and fattening farms.

Functional characterization of the putative FAD synthase from Mycoplasma hyopneumoniae

In bacteria, the biosynthesis of the cofactor flavin adenine dinucleotide (FAD), important in many physiological responses, is catalyzed by the bifunctional enzyme FAD synthase (FADSyn) which converts riboflavin into FAD by both kinase and adenylylation activity. The in silico 3D structure of a putative FADSyn from Mycoplasma hyopneumoniae (MhpFADSyn), the etiological agent of enzootic pneumonia was already reported, nevertheless, the in vitro functional characterization was not yet demonstrated. Our phylogenetic analysis revealed that MhpFADSyn is close related to the bifunctional FADSyn from Corynebacterium ammoniagenes. However, only the domain related to adenylylation was assigned by InterPro database. The activity of MhpFADSyn was evaluated through in vitro enzymatic assays using cell extracts from IPTG-inducible heterologous expression of MhpFADSyn in Escherichia coli. The flavoproteins were analyzed by HPLC and results showed that IPTG-induced cell lysate resulted in the formation of twofold increased amounts of FAD if compared to non IPTG-induced cells. Consumption of riboflavin substrate was also threefold greater in IPTG-induced lysate compared to non IPTG-induced cell extract. Thus, the recombinant MhpFADSyn protein could be associated to FAD biosynthesis. These findings contribute to expand the range of potential drug targets in diseases control and unveil metabolic pathways that could be attribute to mycoplasmas.