Distribution and genetic diversity of Feline calicivirus in Moscow metropolitan area

BACKGROUND

Feline calicivirus (FCV) is widespread throughout the world. An FCV infection is associated with conjunctivitis, rhinitis, and mouth ulcers that can lead to the animal's death. Because vaccination is not always effective, it is necessary to monitor the infection regularly.

OBJECTIVES

This study examined the FCV epizootic situation in the Moscow metropolitan area by conducting a molecular phylogenetic analysis of the virus isolates.

METHODS

Samples from 6213 animals were examined by a reverse transcription polymerase chain reaction. For phylogenetic analysis, 12 nucleotide sequences obtained from animal samples were selected. Sequencing was performed using the Sanger method. Phylogenetic analysis was conducted using the Maximum Likelihood method.

RESULTS

The FCV genome was detected in 1,596 (25.7%) samples out of 6,213. In 2018, calicivirus was detected in 18.9% of samples, 27.8% in 2019, 21.4% in 2020, and 32.6% in 2021. Phylogenetic analysis of the F ORF2 region and the ORF3 start region led to division into two FCV genogroups. Most of the isolates (8 out of 12) were close to the Chinese strains. On the other hand, there were isolates closely related to European and American strains. The isolates circulating in Moscow were not included in clusters with vaccine strains; their nucleotide similarity varied from 77% to 83%.

CONCLUSIONS

This study revealed a high prevalence and genetic diversity of the FCV in Moscow. The epizootic situation remains stably tense because 24 viruses were detected in 25% of animals annually.

Identification and in vitro characterization of a novel porcine parvovirus 6 in Russia

Porcine parvovirus 6 (PPV6) was first identified in aborted swine fetuses in China in 2014. Since its identification, an increased number of PPV6 cases have been reported in many countries with developed pig breeding. In this study, the first identification of porcine parvovirus 6 in Russia, its phylogenetic analysis, and its characterization in vitro are reported. During the investigation, 521 serum samples collected from pigs of different ages from seven regions of the Russian Federation were tested. In four regions, the DNA of the virus was detected. The overall prevalence of porcine parvovirus 6 in Russia was 9.4%. Fattening pigs were the group with the most frequent detection of the virus genome. Phylogenetic analysis of the Russian isolate detected in a domestic boar indicated high homology with strains from Spain. In vitro studies revealed that the most promising cell cultures for PPV6 isolation are SPEV and SK. Our results demonstrated that PPV6 induced typical apoptotic features in cells, including DNA fragmentation, chromatin margination, nuclear condensation, pyknosis of nuclei, symplast formation, and various pathological mitoses.

Distribution and phylogenetic analysis of porcine parvoviruses in the wild boar population of Russia

BACKGROUND

Porcine parvoviruses (PPVs) are widespread worldwide in the swine population. PPV1 is a significant infectious agent in pig production, causing porcine reproductive failure. The pathogenic potential of novel PPVs has been poorly studied. Since wild boars are a reservoir for PPVs, the aim of this study was to investigate their prevalence and genetic diversity in the wild boar population. Tissue samples (spleen, lungs, and lymph nodes) collected from 108 wild boars from three regions of Russia during 2021-2024 were analyzed.

RESULTS

PPV1-7 were found in wild boar populations in Russia, and the most abundant species were PPV7 (59.3%) and PPV3 (49.1%). The research did not reveal any significant relationship between the gender and age of the animals and the prevalence of PPVs. A comparison between the detection rates of PPVs and PCV2/PCV3 revealed the random nature of coinfections. For phylogenetic analysis, complete VP1/VP2 gene sequences of 17 PPV1 isolates were obtained. Most of them belonged to the 27a-like group. Two isolates were in the same cluster as the highly virulent Kresse strain. Isolate BelWB57 had amino acid substitutions that were specific to both the Kresse and 27a-like strains, but it was not classified in either group. Additionally, three sequences for PPV2, PPV3, and PPV7, and one sequence for PPV5 and PPV6 VP1/VP2 genes were obtained. PPV2, PPV3, and PPV7 isolates demonstrated distribution across various clusters with strains from domestic pigs and wild boars from different countries. PPV6 isolate was included in the same clade as the Russian isolate from a domestic pig, whereas PPV5 did not enter any clade with representatives from our country.

CONCLUSIONS

This is the first work devoted to the study of the PPV1-7 prevalence, as well as the genetic characteristics of isolates circulating among wild boars in various regions of Russia. Our data showed that PPV1-7 is widespread in wild boar populations. Phylogenetic analysis of PPV1 demonstrates a significant prevalence of 27a-like isolates.

Genetic diversity of porcine circoviruses 2 and 3 circulating among wild boars in the Moscow Region of Russia

Porcine circoviruses (PCVs) are widely distributed in swine herds. PCV2, the significant swine pathogen, causes infections characterized by growth and development disorders, skin lesions, and respiratory distress. PCV3 has been circulating worldwide and can be associated with various clinical signs and disease developments. Wild boars are the main reservoir of these pathogens in wildlife and can create an alarming threat to pig farming. In Russia, three PCV2 genotypes (PCV2a, PCV2b, and PCV2d) were identified in pig farms. Additionally, PCV3 was observed in pig herds during the monitoring studies in the country. However, data considering the circulation of PCVs in herds of wild boars in Russia is scant. For this purpose, we performed PCR assays of the samples from 30 wild boars hunted in the Moscow Region of Russia in 2021-2023. The ratios of wild boars positive for PCV2, PCV3, or coinfected were 50, 10, and 13.3%, respectively. Additionally, we sequenced 15 PCV2 and four PCV3 complete genomes and conducted phylogenetic analysis, which divided PCV2 isolates into two groups: PCV2d and PCV2b. The study showed a high infection rate of PCV2 among wild boars, with PCV2d dominance. Simultaneously, PCV3 also circulates among wild boars. The obtained results can provide a basis for the development of preventive measures to support infection transmission risks between farm and wild animals.