Genetic characterization of porcine kobuvirus variants identified from healthy piglets in China

Removal of RNA viruses from swine wastewater using anaerobic membrane bioreactor: Performance and mechanisms

The effective removal of viruses from swine wastewater using anaerobic membrane bioreactor (AnMBR) is vital to ecological safety. However, most studies have focused only on disinfectants, whereas the capabilities of the treatment process have not been investigated. In this study, the performance and mechanism of an AnMBR in the removal of porcine hepatitis E virus (HEV), porcine kobuvirus (PKoV), porcine epidemic diarrhea virus (PEDV), and transmissible gastroenteritis coronavirus (TGEV) are systematically investigated. The results show that the AnMBR effectively removes the four viruses, with average removal efficiencies of 1.62, 3.05, 2.41, and 1.34 log for HEV, PKoV, PEDV and TGEV, respectively. Biomass adsorption contributes primarily to the total virus removal in the initial stage of reactor operation, with contributions to HEV and PKoV removal exceeding 71.7 % and 68.2 %, respectively. When the membrane is fouled, membrane rejection dominated virus removal. The membrane rejection contribution test shows the significant contribution of membrane pore foulants (23-76 %). Correlation analysis shows that the surface characteristics and size differences of the four viruses contribute primarily to their different effects on biomass adsorption and membrane rejection. This study provides technical guidance for viral removal during the treatment of high-concentration swine wastewater using an AnMBR.

Complete genomic sequence analysis and intestinal tissue localization of a porcine Kobuvirus variant in China

Porcine kobuvirus (PKV) infection is very common in both healthy pigs and diarrhea pigs throughout the world. However, there is no proof that it causes diarrhea, and little is known about its role in diarrhea. There are only a few reports concerning porcine kobuvirus separation at present, which makes investigating its invasion and pathogenesis mechanisms difficult. This study sequenced the entire genome of a porcine kobuvirus strain termed "Wuhan2020" after it was isolated from intestinal tissue samples of healthy piglets. The analysis results revealed that it shared the most resemblance with the WUH1 strain (89.5%) and belonged to the same evolutionary branch as the Hungarian strain S-1-SUN. The PKV was located using the in situ hybridization (ISH) approach, which revealed that it was colonized in intestinal villus epithelial cells and lymphocytes in the Peyer's patch. In general, we analyzed the genetic evolution of PKV, discovered PKV susceptible cells and determined PKV localization in the intestine of infected pigs, providing a reference for future research.

Epidemiology and genetic characteristics of murine kobuvirus from faecal samples of Rattus losea, Rattus tanezumi and Rattus norvegicus in southern China

Recently, murine kobuvirus (MuKV), a novel member of the family Picornaviridae, was identified in faecal samples of Rattus norvegicus in China. The limited information on the circulation of MuKV in other murine rodent species prompted us to investigate its prevalence and conduct a genetic characterization of MuKV in Rattus losea, Rattus tanezumi and Rattus norvegicus in China. Between 2015 and 2017, 243 faecal samples of these three murine rodent species from three regions in southern China were screened for the presence of MuKV. The overall prevalence was 23.0% (56/243). Three complete MuKV polyprotein sequences were acquired, and the genome organization was determined. Phylogenetic analyses suggested that our sequences were closely related to Chinese strains and belong to the species Aichivirus A in the genus Kobuvirus. Additional studies are required to understand the true prevalence of MuKV in murine rodent populations in China.

KOBUVIRUS DETECTION IN THE CRITICALLY ENDANGERED PYGMY HOG (PORCULA SALVANIA), INDIA

Pygmy hogs (Porcula salvania) are the smallest and rarest wild suid. It is categorized as a Critically Endangered species as per the Red List of the International Union for Conservation of Nature. This study reports the first detection of a single-stranded RNA virus species, Aichivirus C, belonging to the genus Kobuvirus (KobV) and the family Picornaviridae, in pygmy hogs. KobV species are identified as a cause of acute gastroenteritis among children in India. As of now, there exists no report on the detection of KobV in animals from India. We used a detection assay based on reverse transcription-polymerase chain reaction for KobV screening in pygmy hogs from a conservation center in India. The 3D polymerase gene-based molecular analysis revealed KobV presence in the Indian wild suid, pygmy hogs. Of the 15 samples tested, three were found positive for picornaviruses and were negative for rotavirus A, rotavirus C, astrovirus, picobirnavirus and caliciviruses. Nucleotide-based sequence analysis of the partial 3D polymerase gene revealed close identity with porcine KobV from the Czech Republic (JX232619, 90.6%-91.6%) and Hungary (NC_011829, 89.8%-91.6%), wherein one of the current study strains clustered with the Czech Republic JX232619 strain in the phylogenetic tree. Further investigation of the role of KobV in health and disease of pygmy hogs is warranted.

Kobuvirus shedding dynamics in a swine production system and their association with diarrhea

Porcine kobuviruses are widely distributed in swine, but the clinical significance of these viruses remains unclear, since they have been associated with both diarrheic and healthy pigs. In addition, there is a paucity of data on Kobuvirus prevalence in Canadian pig herds. In this study, a total of 181 diarrheic and healthy piglets were monitored and sampled on four occasions, intended to represent the different stages of production. The piglets were sampled at the nursing farms (birth to weaning stage), at the nursery farms (post-weaning stage), and at finishing farms (at the beginning and the end of the fattening stage). Fecal and environmental samples were collected during each life stage. Following viral extraction, Kobuvirus detection by RT-PCR was conducted, and positive samples were sequenced. During the late-nursing stage (6-21 days old), piglets with diarrhea shed more Kobuvirus than healthy individuals. Piglets shed more Kobuvirus during the post-weaning stage (nursery farms) than during any of the other life stages. This was evidenced in individual samples as well as in environmental samples. Over 97% of the sampled piglets shed Kobuvirus at least once in their lifetime. All piglets shedding a Kobuvirus strain or mix of strains at the nursing stage did not appear to shed another porcine kobuvirus strain at a later life stage. Overall, our findings throw light on Kobuvirus shedding dynamics and their potential role in neonatal diarrhea at the nursing stage, which appears to be the point of entry for kobuviruses into swine production systems.

Detection and genetic characterization of kobuvirus in cats: The first molecular evidence from Northeast China

Feline kobuvirus (FeKoV), a novel picornavirus of the genus kobuvirus, was initially identified in the feces of cats with diarrhea in South Korea in 2013. To date, there is only one report of the circulation of kobuvirus in cats in southern China. To investigate the presence and genetic variability of FeKoV in northeast China, 197 fecal samples were collected from 105 cats with obvious diarrhea and 92 asymptomatic cats in Shenyang, Jinzhou, Changchun, Jilin and Harbin regions, Northeast China, and viruses were detected by RT-PCR with universal primers targeting all kobuviruses. Kobuvirus was identified in 28 fecal samples with an overall prevalence of 14.2% (28/197) of which 20 samples were co-infected with feline parvovirus (FPV) and/or feline bocavirus (FBoV). Diarrhoeic cats had a higher kobuvirus prevalence (19.1%, 20/105) than asymptomatic cats (8.7%, 8/92). By genetic analysis based on partial 3D gene, all kobuvirus-positive samples were more closely related to previous FeKoV strains with high identities of 90.5%-97.8% and 96.6%-100% at the nucleotide and amino acid levels. Additionally, phylogenetic analysis based on the complete VP1 gene indicated that all FeKoV strains identified in this study were placed into a cluster, which separated from other reference strains previously reported, and three identical amino acid substitutions were present at the C-terminal of the VP1 protein for these FeKoV strains. Furthermore, two complete FeKoV polyprotein genomes were successfully obtained from two positive samples and designated 16JZ0605 and 17CC0811, respectively. The two strains shared 92.9%-94.9% nucleotide identities and 96.8%-98.4% amino acid identities to FeKoV prototype strains. Phylogenetic analysis indicated that FeKoVs were clustered according to their geographical regions, albeit with limited sequences support. This study provides the first molecular evidence that FeKoV circulates in cats in northeast China, and these FeKoVs exhibit genetic diversity and unique evolutionary trend.

Is Porcine Kobuvirus 1 a Typical Diarrhoeic Pathogen of Piglets?

The objective of this study was to show if porcine kobuvirus 1 (PKV-1) participates in the development of diarrhoea in piglets. The experiments were focused on comparing the occurrence of PKV-1 with the occurrence of rotavirus A (RVA) infection in suckling pigs on Slovak pig farms. A total of 91 rectal swabs of piglets (age < 28 days) were collected from 8 pig farms. RT-PCR was employed to detect PKV-1 through amplification of the 495 bp fragment of the 3D gene using primers KoVF/ KoVR, and RVA was detected through amplification of the 309 bp fragment of the VP6 gene using primers rot3 and rot5. As expected, the detection of RVA in diarrhoeic piglets was 56.8 % (P < 0.01), while only 14.8 % in healthy animals. These results confirm that RVA is one of the main causes of diarrhoea in young piglets. Comparatively, PKV-1 was detected in approximately equal numbers in the same group of both healthy and diarrhoeic pigs, with 74.1 % in healthy animals and 81.1 % in diarrhoeic animals, which was not statistically significant (P < 0.05). The level of co-infection of both viruses was 11.1 % in healthy animals. A portion of 48.6 % (P < 0.01) of diarrhoeic animals were found with RVA and PKV-1 coinfections. The results of this study indicate that while RVA is an enteric virus, PKV-1 cannot confidently be confirmed as an enteric pathogen.

Complete Genome Sequence of a Porcine Kobuvirus Variant Strain from Jiangxi, China

The complete genome sequence of a porcine kobuvirus (PKoV) variant strain, CH/KB-1/2014 from Jiangxi, China, with a 90-nucleotide deletion in the 2B gene, was determined and characterized. This study provides a better understanding of the molecular characteristics and evolution of PKoV in Jiangxi, China.

Porcine kobuvirus 1 in healthy and diarrheic pigs: Genetic detection and characterization of virus and co-infection with rotavirus A

The porcine kobuvirus 1 (PKV-1) is believed to be an enteric virus. To investigate the prevalence of PKV-1 in pigs, virus was detected by RT-PCR in rectal swabs originating from 414 healthy and diarrheic pigs of different age categories on farms in Slovakia. Among all ages of animals, PKV-1 was detected equally in diarrheic (63.8%) and clinically healthy (62.9%) pigs. PKV-1 was more often detected in diarrheic (74.6%) than in healthy (64.4%) suckling piglets (<28days) but data was not statistically significant. Results in weaned (28-70days) and fattening (>70days) of both healthy and diarrheic pigs were inconsistent ranging in interval 56.2% to 67.9%. This study did not confirm a clear relationship of PKV-1 infection with diarrhea in pigs. Rotavirus A infection was detected among the same animals in 39% diarrheic and 9.2% healthy suckling piglets (p<0.001) confirming rotavirus as a causative agent of diarrhea in this age group. The difference was not significant in older pigs with both diarrheic and healthy pigs being infected within a range of 0% to 12.2%. Co-infection with PKV-1 and rotavirus A was detected overall in 5.6% of healthy and in 13.5% of diarrheic pigs and was highest in suckling piglets (33.9%). The PKV-1sequences from pigs in Slovakia were analyzed at the genetic level in the partial 3D gene region for the first time. The viral sequences were grouped in phylogenetic clusters according to their farm of origin. When compared with 157 nucleotide sequences originating from pig samples of different countries around the world Slovakian PKV-1 sequences were clustered in the phylogenetic tree with Asian sequences but not with nucleotide sequences from the neighbouring countries of Czech Republic or Hungary.