Swine Conjunctivitis Associated with a Novel Mycoplasma Species Closely Related to <i>Mycoplasma hyorhinis</i>

• Main Authors: Isabel Hennig-Pauka, Christoph Sudendey, Sven Kleinschmidt, Werner Ruppitsch, Igor Loncaric, Joachim Spergser
• Format: Article
• Language: English
• Published: MDPI AG 2021-12-01
• Series: Pathogens
• Subjects: ammonia; conjunctivitis; lymphohistiocytic inflammation; Mycoplasma sp. nov.; myo-inositol pathway; swine
• Online Access: https://www.mdpi.com/2076-0817/10/1/13

Conjunctivitis in swine is a common finding, usually considered to be a secondary symptom of respiratory or viral systemic disease, or a result of irritation by dust or ammonia, or of local infections with <i>Mycoplasma</i> (<i>M.</i>)<i> hyorhinis</i> or chlamydia. In three unrelated swine farms in Germany with a high prevalence of conjunctivitis, a novel mycoplasma species, tentatively named <i>Mycoplasma</i> sp. 1654_15, was isolated from conjunctival swabs taken from affected pigs. Although 16S rRNA gene sequences shared highest nucleotide similarities with <i>M. hyorhinis</i>, matrix-assisted laser desorption ionization-time of flight (MALDI-TOF) mass spectrometry, partial <i>rpoB</i> sequencing, and comparative whole genome analyses indicated the identification of a novel species within genus <i>Mycoplasma</i>. Noticeable differences between <i>Mycoplasma</i> sp. 1654_15 and <i>M. hyorhinis</i> were the lack of a <i>vlp</i> locus and the presence of a myo-inositol pathway in the genome of strain 1654_15. Since myo-inositol might be used as an alternative energy source by this pathogen on the conjunctival surface, robust colonization by outcompeting other bacteria could be the consequence. In summary, abundant isolation of <i>Mycoplasma</i> sp. 1654_15 from the conjunctiva of affected pigs, its close relationship to <i>M. hyorhinis</i>, and identification of a panel of coding sequences (CDSs) potentially associated with virulence and pathogenicity suggested a local eye disease caused by a so far unknown, highly specialized mycoplasma species.