Attenuation of Mycoplasma hyopneumoniae Strain ES-2 and Comparative Genomic Analysis of ES-2 and Its Attenuated Form ES-2L

Differential domains and endoproteolytic processing in dominant surface proteins of unknown function from Mycoplasma hyopneumoniae and Mycoplasma flocculare

Mycoplasma hyopneumoniae causes porcine enzootic pneumonia (PEP), a chronic respiratory disease that leads to severe economic losses in the pig industry. Swine infection and PEP development depend on the adhesion of the pathogen to the swine respiratory tract and the host immune response, but these and other disease determinants are not fully understood. For instance, M. hyopneumoniae has a large repertoire of proteins of unknown function (PUFs) and some of them are abundant in the cell surface, where they likely mediate so far unknown pathogen-host interactions. Moreover, these surface PUFs may undergo endoproteolytic processing to generate larger repertoires of proteoforms to further complicate this scenario. Here, we investigated the five PUFs more represented on the surface of M. hyopneumoniae pathogenic strain 7448 in comparison with their orthologs from the nonpathogenic M. hyopneumoniae J strain and the closely related commensal species Mycoplasma flocculare. Comparative in silico analyses of deduced amino acid sequences and proteomic data identified differential domains, disordered regions and repeated motifs. We also provide evidence of differential endoproteolytic processing and antigenicity. Phylogenetic analyses were also performed with ortholog sequences, showing higher conservation of three of the assessed PUFs among Mycoplasma species related to respiratory diseases. Overall, our data point out to M. hyopneumoniae surface-dominant PUFs likely associated with pathogenicity.

Mycoplasmas as Host Pantropic and Specific Pathogens: Clinical Implications, Gene Transfer, Virulence Factors, and Future Perspectives

Mycoplasmas as economically important and pantropic pathogens can cause similar clinical diseases in different hosts by eluding host defense and establishing their niches despite their limited metabolic capacities. Besides, enormous undiscovered virulence has a fundamental role in the pathogenesis of pathogenic mycoplasmas. On the other hand, they are host-specific pathogens with some highly pathogenic members that can colonize a vast number of habitats. Reshuffling mycoplasmas genetic information and evolving rapidly is a way to avoid their host's immune system. However, currently, only a few control measures exist against some mycoplasmosis which are far from satisfaction. This review aimed to provide an updated insight into the state of mycoplasmas as pathogens by summarizing and analyzing the comprehensive progress, current challenge, and future perspectives of mycoplasmas. It covers clinical implications of mycoplasmas in humans and domestic and wild animals, virulence-related factors, the process of gene transfer and its crucial prospects, the current application and future perspectives of nanotechnology for diagnosing and curing mycoplasmosis, Mycoplasma vaccination, and protective immunity. Several questions remain unanswered and are recommended to pay close attention to. The findings would be helpful to develop new strategies for basic and applied research on mycoplasmas and facilitate the control of mycoplasmosis for humans and various species of animals.