Molecular chracterisation of porcine group A rotaviruses: Studies on the age-related occurrence and spatial distribution of circulating virus genotypes in Poland

Isolation, characterization and whole-genome analysis of G9 group a rotaviruses in China: Evidence for possible Porcine-Human interspecies transmission

Group A rotaviruses (RVAs) are major causes of severe gastroenteritis in infants and young animals. To enhance our understanding of the relationship between human and animals RVAs, complete genome data are necessary. We screened 92 intestinal and stool samples from diarrheic piglets by RT‒PCR targeting the VP6 gene, revealing a prevalence of 10.9%. RVA was confirmed in two out of 5 calf samples. We successfully isolated two porcine samples using MA104 cell line. The full-length genetic constellation of the two isolates were determined to be G9-P[23]-I5-R1-C1-M1-A8-N1-T7-E1-H1, with close similarity to human Wa-like and porcine strains. Sequence analysis revealed the majority of genes were closely related to porcine and human RVAs. Phylogenetic analysis revealed that these isolates might have their ancestral origin from pigs, although some of their gene segments were related to human strains. This study reveals evidence of reassortment and possible interspecies transmission between pigs and humans in China.

Rotavirus A in Domestic Pigs and Wild Boars: High Genetic Diversity and Interspecies Transmission

Rotavirus A (RVA) is an important pathogen for porcine health. In comparison to humans, RVA in domestic animals and especially in wildlife is under researched. Therefore, the aim of the present study was to investigate the prevalence, genetic diversity, molecular epidemiology and interspecies transmission of RVA in domestic pigs and wild boars. During the three consecutive RVA seasons (2018–2021) we collected 445 and 441 samples from domestic pigs and wild boars, respectively. Samples were tested by real-time RT-PCR, and RVA-positive samples were genotyped in VP7 and VP4 segments. Our results report an RVA prevalence of 49.9% in domestic pigs and 9.3% in wild boars. Outstanding RVA genetic diversity was observed in VP7 and VP4 segments, especially in domestic pigs exhibiting a striking 23 different RVA combinations (G5P[13] and G9P[23] prevailed). Interspecies transmission events were numerous between domestic pigs and wild boars, sharing G3, G5, G6, G9, G11 and P[13] genotypes. Furthermore, our data indicate that such transmission events involved even bovines (G6, P[11]) and, intriguingly, humans (G1P[8]). This study contributes to the basic knowledge that may be considered important for vaccine development and introduction, as a valuable and currently missing tool for efficient pig health management in the EU.

Prevalence and diversity of rotavirus A in pigs: Evidence for a possible reservoir in human infection

BACKGROUND

Rotavirus A (RVA) are a group of diverse viruses causing acute gastroenteritis (AGE) in humans and animals. Zoonotic transmission is an important mechanism for rotavirus evolution and strain diversity in humans, but the extent of pigs as a major reservoir for human infection is not clear.

METHODS AND FINDINGS

We have surveyed 153 pig farms across Taiwan with a total of 4588 porcine stool samples from three age groups from 2014 to 2017. Nursing piglets (less than one month of age) had higher detection rate for rotavirus than older age groups. Five VP7 (G) genotypes and 5 VP4 (P) genotypes were found in a total of 14 different G/P genotype combinations. In addition, porcine RVA strains had 2 NSP4 (E) genotypes and 3 VP6 (I) genotypes. A P[3]-like genotype was also discovered among strains collected in 2016 and 2017.

CONCLUSIONS

Most of the genes from Taiwanese porcine strains clustered with each other and the lineages formed by these strains were distinct from the sequences of numerous regional variants or globally circulating porcine strains, suggesting an independent evolutionary history for Taiwanese rotavirus genotypes. The close relationship among porcine RVA strains and some unique porcine-like genotypes detected sporadically among human children in swine farms illustrates that pigs might serve as a reservoir for potential zoonotic transmission and novel genotype evolution in Taiwan's insular environment.

Genetic Diversity and Epidemiological Significance of Wild Boar HEV-3 Strains Circulating in Poland

The wild boar is the most important reservoir of zoonotic HEV-3 strains among different wildlife species. The aim of the study was subtype identification of wild boar HEV-3 strains circulating in Poland. Wild boar liver was used in the study in the form of homogenates prepared from 57 samples positive for HEV in a real-time RT-PCR. These samples were collected from juvenile and adult wild boars hunted in the jurisdictions of different Regional Directorates of State Forests (RDSF) across Poland. Subtype identification of detected HEV strains was based on a phylogenetic analysis of the most conserved HEV ORF2 genome fragment. Out of 57 tested samples, consensus HEV ORF2 sequences of 348 bp were obtained for 45 strains. Nineteen strains were identified and belonged to the HEV gt 3a and 3i subtypes, whereas 26 were not assigned to any virus subtype. HEV gt 3i strains prevailed in the Polish wild boar population, 16 of such were identified, and they were significantly more often observed in the RDSF Katowice area (χ² = 28.6, p = 0.027 (<0.05)) compared to other regions of the country. Circulation of 3a strains was limited only to the RDSF Gdańsk territory (χ² = 48, p = 0.000 (<0.05)). The virus strains detected in the Polish population of wild boars representing previously identified HEV subtypes in wild boars, pigs, or humans in Europe are of epidemiological importance for public health.

Detection of hepatitis E virus (rabbit genotype) in farmed rabbits entering the food chain

Hepatitis E virus (HEV) infects humans and many animal species. The rabbit HEV has been found in farmed, wild and pet rabbits as well as in human patients suggesting zoonotic transmission. Although the routes of human infection with rabbit strains are unclear a foodborne transmission is suggested especially when asymptomatically infected animals could enter the food chain. The aims of the study were an evaluation of the prevalence of HEV infections in slaughtered rabbits, identification of the virus genotype(s) and assessment of their genetic relatedness to other zoonotic HEV strains. A pair of blood and liver samples (n = 482) were collected from meat rabbits of different breeds slaughtered at the age of 2.8 to 6 months. The animals originated from 20 small-scale and 4 large-scale commercial farms operating in Poland. The presence of anti-HEV antibodies in animals was detected by the use of a recomWell HEV IgG (human) ELISA kit (Mikrogen Diagnostik) adapted to rabbit sera. The isolation of HEV and sample process control virus (feline calicivirus) RNA from homogenates of liver destined for food and virus-positive sera was performed using a QIAamp® Viral RNA Mini Kit (Qiagen). A one-step real-time reverse transcription PCR method containing a target-specific internal amplification control was used for detection of HEV. The (sub)genotype of detected rabbit HEV strains was identified based on sequence analysis of the ORF2 and ORF2/3 virus genome fragments. Anti-HEV antibodies were detected in 29 (6%) out of 482 rabbit sera samples collected from animals raised only on the small-scale rabbit farms. Four sera were also positive for HEV RNA. Viral RNA was detected in 72 (14.9%) animal livers. Analysing ELISA and PCR results using Student's t-test, there were significant differences observed in the frequency of HEV infections between rabbits from small-scale and commercial farms (t = 2.675, p = 0.015 < 0.05 for ELISA and t = 2.705, p = 0.014 < 0.05 for PCR). All detected virus strains were identified as HEV gt3 ra subtype. The results of this study provide data on the occurrence of HEV infections in rabbits entering the food chain, suggesting that a risk of foodborne HEV infection due to consumption of contaminated meat and liver exists. In this light, the presence of rabbit HEV in food animals is pertinent as an issue of food safety and the surveillance of these animals for emerging or re-emerging viruses.