A genetic and virulence characterization of Brazilian strains of Mycoplasma hyopneumoniae

Leonardo Teófilo Toledo; Luiz Fernando Lino de Souza; Carlos Eduardo Real Pereira; Richard Costa Polveiro; Gustavo Costa Bressan; Ricardo Seiti Yamatogi; Kwangcheol Casey Jeong; Fernanda Simone Marks; Caio Augustus Diamantino; Victor Hugo Rabelo de Carvalho; Clarisse Sena Malcher; Fernando Antônio Moreira Petri; Luis Guilherme de Oliveira; Maria Aparecida Scatamburlo Moreira; Abelardo Silva-Júnior

doi:10.3389/fmicb.2023.1280588

A genetic and virulence characterization of Brazilian strains of Mycoplasma hyopneumoniae

Front Microbiol. 2023 Nov 22:14:1280588. doi: 10.3389/fmicb.2023.1280588. eCollection 2023.

Authors

Leonardo Teófilo Toledo¹, Luiz Fernando Lino de Souza¹, Carlos Eduardo Real Pereira¹, Richard Costa Polveiro¹, Gustavo Costa Bressan², Ricardo Seiti Yamatogi¹, Kwangcheol Casey Jeong³, Fernanda Simone Marks¹, Caio Augustus Diamantino¹, Victor Hugo Rabelo de Carvalho¹, Clarisse Sena Malcher⁴, Fernando Antônio Moreira Petri⁴, Luis Guilherme de Oliveira⁴, Maria Aparecida Scatamburlo Moreira¹, Abelardo Silva-Júnior⁵

Affiliations

¹ Department of Veterinary Medicine, Federal University of Viçosa, Viçosa, Brazil.
² Department of Biochemistry and Molecular Biology, Federal University of Viçosa, Viçosa, Brazil.
³ Emerging Pathogens Institute, University of Florida, Gainesville, FL, United States.
⁴ School of Agricultural and Veterinarian Sciences, São Paulo State University (Unesp), São Paul, Brazil.
⁵ Institute of Biological and Health Sciences, Federal University of Alagoas, Maceió, Brazil.

Abstract

Mycoplasma hyopneumoniae (M. hyopneumoniae) is considered the primary causative agent of porcine enzootic pneumonia (EP), a chronic contagious respiratory disease that causes economic losses. Obtaining new pathogenic isolates and studying the genome and virulence factors are necessary. This study performed a complete sequencing analysis of two Brazilian strains, UFV01 and UFV02, aiming to characterize the isolates in terms of the virulence factors and sequence type. The complete genome analysis revealed the main virulence genes (mhp385, mhp271, MHP_RS03455, p102, p97, p216, MHP_RS00555, mhp107) and ST-123, the presence of three toxin-related genes (tlyC, PLDc_2 and hcnC), and some genetic groups specific to these two isolates. Subsequently, the pathogenicity of the isolates was evaluated via an experimental infection conducted in a swine model. The study was divided into three groups, namely a negative control group (n = 4) and two test groups (n = 8), totaling 20 animals. They were challenged at 35 days of age with 10⁷ CCU (Color Changing Units) M. hyopneumoniae via the intratracheal route. The UFV01 group showed earlier and higher seroconversion (IgG) (100%), while only 50% of the UFV02 group seroconverted. The same trend was observed when analyzing the presence of IgA in the bronchoalveolar lavage fluid (BALF) at 35 days post-infection (dpi). The UFV01 group had a mean macroscopic lesion score of 11.75% at 35 dpi, while UFV02 had 3.125%. Microscopic lesions were more severe in the UFV01 group. Based on laryngeal swab samples evaluated by qPCR, and the detection began at 14 days. The UFV01 group showed 75% positivity at 14 dpi. The UFV02 group also started excreting at 14 dpi, with a positivity rate of 37.5%. The results indicate that the UFV01 isolate exhibits higher virulence than UFV02. These findings may aid in developing new vaccines and diagnostic kits and establishing experimental models for testing.

Keywords: Swine. Mycoplasma hyopneumoniae; UFV01; UFV02; experimental challenge; genome; lesion; respiratory disease; virulence.

Grants and funding

The author(s) declare financial support was received for the research, authorship, and/or publication of this article. This work was supported by Brazilian agencies: Minas Gerais State Agency for Research and Development (FAPEMIG, grant #APQ-01327-14), National Council for Scientific and Technological Development (CNPq, grant #304727/2016-4), Coordination for the Improvement of Higher Education Personnel (CAPES, grant #Finance code 001) and Foundation for Research Support of the State Alagoas (FAPEAL, grant # APQ2022021000101).