Molecular-biological study of causes of persistent chlamydial infection in cattle: application of developed pcr test system for detecting chlamydophila abortus

Chlamydial infections in animals are a serious problem spread across many continents. Despite the fact that 22% of the world's countries have reported cases of chlamydial infection in animals, the actual prevalence of this disease may be much higher due to the difficulty of diagnosing it. To date, there is no commercial PCR kit for the detection of Chlamydophila abortus in the Russian Federation. In this regard, the main goal of our study was to conduct a molecular genetic study of the causative agent of chlamydial infection in cattle, using a primer PCR test system developed and optimized by us to detect the genomic DNA of species-specific Chlamydophila abortus. To achieve this goal, we conducted a retrospective analysis of the epizootological situation regarding chlamydial infections of cattle in the territory of 2 constituent entities of the Russian Federation. Molecular biological studies of species identification of causative agents of chlamydial infection in cattle were carried out using commercial PCR kits and an optimized primer system to detect genomic DNA of species-specific Chlamydophila abortus. A retrospective analysis showed that in 2018-2022, “chlamydial infection” was diagnosed in 13.4% of cases. In 51.2% of cases, DNA from the pathogen Chlamydophila pecorum was present; in 19.5% of cases - Chlamydophila abortus, in 29.3% of cases - Chlamydia spp. Molecular genetic studies using an optimized primer test system to identify specific DNA regions of Chlamydophila abortus allowed us to identify the genomes of this pathogen in 34% of cases. DNA from Chlamydophila pecorum and Chlamydophila psittaci was also found in the samples. Most often, Chlamydophila abortus DNA was isolated from cow vaginal swabs - 68.8%, less often from internal organs from dead animals. The developed primer test system is an effective tool for the differential diagnosis of chlamydial infections in cattle, which can provide control over the epizootic situation for this disease.

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