Mycoplasma hyopneumoniaevariability:Current trends and proposed terminology for genomic classification

Abstract

Mycoplasma hyopneumoniae (M. hyopneumoniae) is the aetiologic agent of enzootic pneumonia in swine, a prevalent chronic respiratory disease worldwide. Mycoplasma hyopneumoniae is a small, self-replicating microorganism that possesses several characteristics allowing for limited biosynthetic abilities, resulting in the fastidious, hostspecific growth and unique pathogenic properties of this microorganism. Variation across several isolates of M. hyopneumoniae has been described at antigenic, proteomic, transcriptomic, pathogenic and genomic levels. The microorganism possesses a minimal number of genes that regulate the transcription process. Post-translational modifications (PTM) occur frequently in a wide range of functional proteins. The PTM by which M. hyopneumoniae regulates its surface topography could play key roles in cell adhesion, evasion and/or modulation of the host immune system. The clinical outcome of M. hyopneumoniae infections is determined by different factors, such as housing conditions, management practices, co-infections and also by virulence differences among M. hyopneumoniae isolates. Factors contributing to adherence and colonization as well as the capacity to modulate inflammatory and immune responses might be crucial. Different components of the cell membrane (i.e. proteins, glycoproteins and lipoproteins) may serve as adhesins and/or be toxic for the respiratory tract cells. Mechanisms leading to virulence are complex and more research is needed to identify markers for virulence. The utilization of typing methods and complete or partial-gene sequencing for M. hyopneumoniae characterization has increased in diagnostic laboratories as control and elimination strategies for this microorganism are attempted worldwide. A commonly employed molecular typing method for M. hyopneumoniae is Multiple-Locus Variable number tandem repeat Analysis (MLVA). The agreement of a shared terminology and classification for the various techniques, specifically MLVA, has not been described, which makes inferences across the literature unsuitable. Therefore, molecular trends for M. hyopneumoniae have been outlined and a common terminology and classification based on Variable Number Tandem Repeats (VNTR) types has been proposed. K E Y W O R D S genomic classification, Mycoplasma hyopneumoniae, terminology, variability, Variable Number Tandem Repeats | 1841 BETLACH ET AL.

Genomic variability of Mycoplasma hyopneumoniae within pig lung lobes

“…The present study using VNTR typing based on four loci showed a high genomic variability of M. hyopneumoniae among the investigated population. The terminology and classification of the MLVA assay followed recently proposed criteria [ 1 ] specific for M. hyopneumoniae . The genomic variability observed in this study is consistent with what has been observed in previous studies, either in specific geographic regions [ 3 ] or at the farm level [ 11 ].…”

“…Currently, M. hyopneumoniae genomic classification and the corresponding terminology follow the definition of VNTR types [ 1 ]. Preliminary studies of the association between the severity of Mycoplasma -like lung lesions and the number of different genotypes revealed no association [ 2 ] or a positive association [ 12 ].…”

Pathogenicity & virulence ofMycoplasma hyopneumoniae

“…Preventing strategies to avoid the introduction of the pathogen in farms free of M. hyopneumoniae are also important. Garza-Moreno et al [50] presented different M. hyopneumoniae monitoring strategies of incoming gilts and recipient herds and proposed a farm classification based on their health status. According to clinical signs, lung lesions, and ELISA and PCR results, farms and incoming replacements can then be classified into negative, provisional negative and positive.…”

“…Vaccination is today still regarded as the most effective way to control M. hyopneumoniae infections. Gilt replacement acclimation procedures against M. hyopneumoniae in positive farms in Europe and North America showed that vaccination is the main strategy to avoid EP [50]. Anti-M. hyopneumoniae vaccines are used worldwide and consist mainly of inactivated, adjuvanted whole-cell preparations that are administered intramuscularly [27].…”

Genomic Variability and Post-translational Protein Processing Enhance the Immune Evasion of Mycoplasma hyopneumoniae and Its Interaction With the Porcine Immune System

“…Results from other experimental methods also supported the genomic variability between Mhp strains, including multiple locus variable number tandem repeat analysis (MLVA) (13, [16][17][18], random amplified polymorphic DNA (RAPD) analysis, pulsed-field gel electrophoresis and nested polymerase chain reaction (nPCR) (19)(20)(21)(22). This review (23) provides detailed information about the Mhp genomic classification and variability.…”