An Outbreak of a Respiratory Disorder at a Russian Swine Farm Associated with the Co-Circulation of PRRSV1 and PRRSV2.

We conducted a cross-sectional study to identify the major respiratory pathogen responsible for an outbreak of respiratory disease at a swine farm in West Siberia in 2019. We discovered that the peak of morbidity and mortality coincided with a high level of porcine reproductive and respiratory syndrome virus (PRRSV) 1 and 2-related viremia. Based on longer PRRSV2 viremia, the dominant role of PRRSV2 over PRRSV1 in the outbreak was assumed. Phylogenetic analysis revealed that the PRRSV1 strain belonged to sub-genotype 2-one of the predominant groups of genotype 1 PRRSVs in Russia. A partial open reading frame 7 sequence of the PRRSV2 isolate demonstrated a high identity with modified live vaccine-related strains from Denmark (93%) and wild-type VR2332 (92%). We identified the first instance of PRRSV1/PRRSV2 mixed infection in Russia. This finding indicates that further field investigations are needed to access PRRSV2 epidemiology in eastern Europe.

First detection and full genome sequence of porcine circovirus type 3 in Russia.

Porcine circovirus type 3 (PCV3) was firstly detected in 2016 in USA. Later PCV3 was discovered in Asia, Europe, and South America. The present investigation demonstrates for the first time the circulation of PCV3 among pigs in Russia. The viruses were detected at two geographically distant unrelated commercial farms with records of reproductive failure (abortions, stillbirth), porcine dermatitis, and nephropathy syndrome (PDNS). The two farms were located in the region of Smolensk (western part of Russia) and the region of Tyumen (West Siberia, Russia). We investigated samples collected from pigs of different ages. We performed PCR for the PCV3 DNA detection. The DNA of PCV3 was detected in serum, kidney, heart, spleen, pleural effusion, and peritoneal cavity fluid samples. Two viral genomes were sequenced and the corresponding strains were named PCV3-RU/SM17 (the strain from Smolensk region) and PCV3-RU/TY17 (the strain from Tyumen region). The full genome sequences of both strains were 2000 nucleotides in length and contained at least two ORFs, encoding the Cap and Rep proteins. Full sequence alignment revealed a 99.3% identity between the PCV3-RU/SM17 and PCV3-RU/TY17 strains. Molecular analysis showed that the two strains from Russia are highly homologous to viruses identified in other countries, with a 98.5-99.6% homology for PCV3-RU/TY17 and 97.9-99.0 for PCV3-RU/SM17. The PCV3-RU/SM17 and PCV3-RU/TY17 strains were found to form a monophyletic group in a phylogenetic tree based on PCV3 complete genome sequences.

Genome Characterization of a Pathogenic Porcine Rotavirus B Strain Identified in Buryat Republic, Russia in 2015.

An outbreak of enteric disease of unknown etiology with 60% morbidity and 8% mortality in weaning piglets occurred in November 2015 on a farm in Buryat Republic, Russia. Metagenomic sequencing revealed the presence of rotavirus B in feces from diseased piglets while no other pathogens were identified. Clinical disease was reproduced in experimentally infected piglets, yielding the 11 RVB gene segments for strain Buryat15, with an RVB genotype constellation of G12-P[4]-I13-R4-C4-M4-A8-N10-T4-E4-H7. This genotype constellation has also been identified in the United States. While the Buryat15 VP7 protein lacked unique amino acid differences in the predicted neutralizing epitopes compared to the previously published swine RVB G12 strains, this report of RVB in Russian swine increases our epidemiological knowledge on the global prevalence and genetic diversity of RVB.

Genetic and pathogenic characterization of a Russian subtype 2 PRRSV-1 isolate.

Porcine reproductive and respiratory syndrome virus (PRRSV) causes reproductive failure and respiratory problems. Data about the virulence and pathogenicity of subtype 2 PRRSV-1 strains are limited. The main purposes of this investigation were to characterize the full genome sequence of the subtype 2 PRRSV-1 WestSib13 strain and to compare the pathogenicity with that of the subtype 1 PRRSV-1 Lelystad strain. Comparison of the whole genome sequence of the WestSib13 strain with that of PRRSV-1 prototype strains revealed a 76.2% (subtype 1 Lelystad virus) and 79.0% (subtype 3 Lena virus) identity, respectively The virulence and pathogenicity of the European subtype 2 PRRSV strain WestSib13 and the European subtype 1 PRRSV strain Lelystad were compared in 3-week-old piglets upon inoculation of 105.4 TCID50 of virus. Non-infected animals (control group) as well as animals infected with the Lelystad strain were clinically healthy until 14days post challenge. In contrast, animals infected with the WestSib13 strain demonstrated dyspnea starting at 3days post-inoculation (dpi). All piglets in this group died between 5 and 8 dpi. During that period, fever was not observed in WestSib13-infected animals. Viremia was detected in animals from both infected groups starting from 2 dpi. Viral loads in serum and lungs upon euthanasia were significantly higher (3 log10) in the WestSib13-infected than in the LV-infected animals. Taken together, this study provides the full genome sequence and the unusual virological and clinical outcome (high level viremia without fever) of the novel WestSib13 strain.