Molecular Differentiation of Mycoplasma gallisepticum Outbreaks: A Last Decade Study on Italian Farms Using GTS and MLST

Abstract

Mycoplasma gallisepticum (MG) infects many avian species and leads to significant economic losses in the poultry industry. Transmission of this pathogen occurs both horizontally and vertically, and strategies to avoid the spread of MG rely on vaccination and the application of biosecurity measures to maintain breeder groups as pathogen-free. Two live attenuated MG vaccine strains are licensed in Italy: 6/85 and ts-11. After their introduction, the implementation of adequate genotyping tools became necessary to distinguish between field and vaccine strains and to guarantee proper infection monitoring activity. In this study, 40 Italian MG isolates collected between 2010–2019 from both vaccinated and unvaccinated farms were genotyped using gene-targeted sequencing (GTS) of the cythadesin gene mgc2 and multilocus sequence typing (MLST) based on six housekeeping genes. The discriminatory power of GTS typing ensures 6/85-like strain identification, but the technique does not allow the identification ts-11 strains; conversely, MLST differentiates both vaccine strains, describing more detailed interrelation structures. Our study describes MG genetic scenario within a mixed farming context. In conclusion, the use of adequate typing methods is essential to understand the evolutionary dynamics of MG strains in a particular area and to conduct epidemiological investigations in the avian population.

Targeted Sequencing Analysis Of Mycoplasma Gallisepticum Isolates In Chicken Layer And Breeder Flocks In Thailand.

“…This study is the rst study which GTS technique have been done on Thai MG strains with 4 partial MG gene sequences. Partial mgc gene was used for MG characterization in many epidemiological studies 6,14,18 . mgc2 gene encodes MGC2 protein which works with gapA gene encoded protein for cell attachment 19 , involving with MG immunogenicity 20,21 .…”

“…However, using only single gene for MG classi cation could not indicate the similarity between MG isolates. There were MG isolates were negative by PCR assay with mgc2 gene detection resulting in a failure to obtain mgc2 sequences 5,6,13,16 , indicating that only one partial gene sequence cannot be used to characterize MG gene.…”

“…There were some Thai MG isolates could not be obtained DNA sequences with all 4 virulence genes. For example, Thai MG isolate AHRU/2009/CU3704 could only be classi ed by phylogenetic of gapA and pvpA genes because it was negative with PCR method using mgc2 and pvpA primers speci c. Plausibly, it might be the quality of DNA and/or the genetic mutation in inter-and intra-strain MG 6,22,23 .…”

“…Therefore, the differentiation technique to identify between vaccine and eld MG strains in suspected MG infection ock is needed. Several studies have investigated the techniques for MG classi cation [4][5][6][7] . The most used technique in Thailand is random ampli cation of polymorphic DNA (RAPD).…”

Targeted sequencing analysis of Mycoplasma gallisepticum isolates in chicken layer and breeder flocks in Thailand

“…For example, gene targeted sequencing (GTS) analysis was developed by Ferguson et al 4 This technique has been used to determine the gene sequences of partial surface proteins of MG, including the gap A, mgc 2, pvp A and MGA_0319 genes. The multilocus sequence typing scheme (MLST) is a technique that many studies have used and is regarded as the gold standard for bacterial typing 6 , 10 , 11 . This technique uses MG housekeeping genes for molecular identification, which is an effective way to determine the relationship between MG strains.…”