Karthik Kumaragurubaran, Anbazhagan Subbaiyan, Chitra Murugesan Ananda, Sridhar Ramaswamy
Central University Laboratory, Tamil Nadu Veterinary and Animal Sciences University, Chennai, Tamil Nadu, 600051, India.
Department of Veterinary Microbiology, Veterinary College and Research Institute, Tamil Nadu Veterinary and Animal Sciences University, Udumalpet, Tamil Nadu, India.
Arch Microbiol. 2022 Oct 6;204(11):663. doi: 10.1007/s00203-022-03276-z.
Moraxella bovoculi has been isolated frequently from cattle with Infectious bovine keratoconjunctivitis (IBK). Two diverse genotypes of M. bovoculi, 1 and 2 were identified based on whole genome sequence analysis. It is essential to discriminate between the two genotypes to frame prevention and control measures. The whole genome of M. bovoculi TN7 was sequenced and compared to other M. bovoculi strains available in the NCBI database. M. bovoculi TN7 was found to be genotype 1, had an RTX toxin operon and pilA gene that are the known virulence factors in related Moraxella sp., but lacked antimicrobial resistance genes. M. bovoculi was found to have an open pangenome with 4051 (75.31%) accessory genes, and the addition of each new genome adds 18 genes to the pangenome. Comparison of pilin protein amino acid sequences revealed three new sequence types. Furthermore, the presence of linx, nagL, swrC and mdtA genes was found to be genotype 1 specific, whereas hyaD, garR, gbsA, yhdG, gabT, iclR, higB2, hmuU, hmuT and hemS were found only in genotype 2. Polymerase Chain Reaction (PCR) primers were designed and evaluated on strain TN7 plus seven additional strains accessible to us that had not been whole genome sequenced. This initial evaluation of the designed primers for the linX and hyaD genes produced the expected banding patterns on PCR gels for genotypes 1 and 2, respectively, among the 8 strains. The genotype-specific genes identified in this study can be used as markers for accurate diagnosis of genotype 1 isolates and this can aid in the development of autogenous or other molecular vaccines for treatment of infectious bovine keratoconjunctivitis (IBK) in resource-limited research settings.
牛眼莫拉菌经常从患有传染性牛角膜结膜炎（IBK）的牛中分离出来。基于全基因组序列分析，鉴定出了牛眼莫拉菌的两种不同基因型，即1型和2型。区分这两种基因型对于制定预防和控制措施至关重要。对牛眼莫拉菌TN7的全基因组进行了测序，并与NCBI数据库中现有的其他牛眼莫拉菌菌株进行了比较。发现牛眼莫拉菌TN7为1型，具有RTX毒素操纵子和pilA基因，这些是相关莫拉菌属中已知的毒力因子，但缺乏抗菌抗性基因。发现牛眼莫拉菌具有一个开放的泛基因组，其中有4051个（75.31%）辅助基因，每增加一个新基因组，泛基因组就会增加18个基因。菌毛蛋白氨基酸序列的比较揭示了三种新的序列类型。此外，发现linx、nagL、swrC和mdtA基因是1型特异性的，而hyaD、garR、gbsA、yhdG、gabT、iclR、higB2、hmuU、hmuT和hemS仅在2型中发现。设计了聚合酶链反应（PCR）引物，并在菌株TN7以及另外7株我们可获得但未进行全基因组测序的菌株上进行了评估。对linX和hyaD基因设计引物的初步评估在8株菌株中分别产生了1型和2型在PCR凝胶上预期的条带模式。本研究中鉴定出的基因型特异性基因可作为准确诊断1型分离株的标志物，这有助于在资源有限的研究环境中开发用于治疗传染性牛角膜结膜炎（IBK）的自体疫苗或其他分子疫苗。
