Three-Level Mixed-Effects Logistic Regression Analysis Reveals Complex Epidemiology of Swine Rotaviruses in Diagnostic Samples from North America

The synergy of recombinant NSP4 and VP4 from porcine rotavirus elicited a strong mucosal response

Porcine rotavirus (PoRV) is one of the main pathogens causing diarrhea in piglets, and multiple genotypes coexist. However, an effective vaccine is currently lacking. Here, the potential adjuvant of nonstructural protein 4 (NSP4) and highly immunogenic structural protein VP4 prompted us to construct recombinant NSP486-175aa (NSP4*) and VP426-476aa (VP4*) proteins, combine them as immunogens to evaluate their efficacy. Results indicated that NSP4* enhanced systemic and local mucosal responses induced by VP4*. The VP4*-IgG, VP4*-IgA in feces and IgA-secreting cells in intestines induced by the co-immunization were significantly higher than those induced by VP4* alone. Co-immunization of NSP4* and VP4* also induced strong cellular immunity with significantly increased IFN-λ than the single VP4*. Summarily, the NSP4* as a synergistical antigen exerted limited effects on the PoRV NAbs elevation, but conferred strong VP4*-specific mucosal and cellular efficacy, which lays the foundation for the development of a more effective porcine rotavirus subunit vaccine.

Interspecies recombination in NSP3 gene in the first porcine rotavirus H in Russia identified using nanopore-based metagenomic sequencing

During the last decade, porcine rotavirus H was detected in the USA, Asian regions, South Africa, Brazil, and a couple of European countries. In the presented study, the virus was identified in piglets on a farrow-to-finish farm in Russia during metagenomic surveillance. Currently, it is the first identification of this species in the country. As a diagnostic method, nanopore-based metagenomic sequencing was applied. The obtained nanopore reads allowed for the assembly of 10 genome segments out of 11. The phylogenetic analysis revealed the virus belonged to the porcine cluster and had GX-P3-I3-R3-C3-M8-A7-N1-T5-E3-H3 genome constellation. Moreover, three potential new genotype groups for VP3, NSP1, and NSP3 genes were determined. Additionally, a recombination between RVH and RVC in the NSP3 gene was detected. The study provides significant information about a novel RVH strain.

Evaluating natural planned exposure protocols on rotavirus shedding patterns in gilts and the impact on their suckling pigs

Objective: The objectives of this study were to determine the pattern of rotavirus A (RVA), rotavirus B (RVB), and rotavirus C (RVC) shedding in gilts after natural planned exposure (NPE) administration and assess the effects on piglet weaning weight, preweaning mortality, and RV shedding. Materials and methods: A total of 70 pregnant gilts were enrolled and allocated into 4 groups. Group 1 was given NPE at 5, 4, and 3 weeks prefarrowing (WPF); Group 2 at 5 and 3 WPF; and Group 3 at 5 WPF only. Group 4 (control group) did not receive any NPE. Samples from 46 gilts and litters (5 piglets/litter) were tested at 12 sample times. Piglets were sampled weekly from 24 hours of age until 6 weeks of age and tested by quantitative reverse transcriptase-polymerase chain reaction for RVA, RVB, and RVC. Results: There was a significant improvement in weaning weight of piglets born to gilts that received 3 NPE administrations compared to fewer or no NPE administrations. Shedding of RVA and RVB from piglets were well controlled in the farrowing room regardless of treatment group, but RVC was observed as early as 1 week old. This study was conducted on a single farm, and the results should be carefully interpreted with knowledge of variations in farms and systems. Implications: Three administrations of NPE to gilts prefarrowing had valuable production and economic benefits for the producer. Circulation patterns of RVA, RVB, and RVC appear to correlate; interventions for one have value against the others.

Antibody Response to Rotavirus C Pre-Farrow Natural Planned Exposure to Gilts and Their Piglets

A longitudinal study was conducted to investigate the dynamics of genotype-specific (G6 and P[5]) antibody response to different doses (3, 2 and 1) of rotavirus C (RVC) natural planned exposure (NPE) in gilt serum, colostrum/milk and piglet serum, and compare with antibody response to rotavirus A NPE (RVA genotypes G4, G5, P[7] and P[23]). G6 and P[5] antigens of RVC were expressed in mammalian and bacterial cells, and used to develop individual indirect ELISAs. For both antigens, group 1 with 3 doses of NPE resulted in significantly higher IgG and IgA levels in colostrum compared to other groups. In piglet serum, group 1 P[5] IgG levels were significantly higher than other study groups at day 0 and 7. Piglet serum had higher IgA levels for group 1 piglets compared to other groups for both antigens. A comparison of colostrum antibody levels to rotavirus A (RVA) and RVC revealed that colostrum RVC IgG and IgA titers were lower than RVA titers irrespective of the G and P-type. Next generation sequencing (NGS) detected same RVC genotypes (G6 and P[5]) circulating in the piglet population under the window of lactogenic immunity. We conclude that the low RVC load in NPE material (real-time PCR Ct-values 32.55, 29.32 and 30.30) failed to induce sufficient maternal immunity in gilts (low colostrum RVC antibody levels) and passively prevent piglets from natural RVC infection in the farrowing room. To the best of our knowledge, this is the first study comparing differences in antibody response to porcine RVA and RVC in a commercial setting.

Assessment of seasonality of rotavirus PCR detection in swine from Ontario and Quebec between 2016-2020 using submissions to a diagnostic laboratory

The goal of this study was to determine if seasonality of rotavirus A, B, and C infection is present in Ontario and Quebec swine herds by investigating submissions to a diagnostic laboratory. Samples (N = 1557) within 755 case submissions from Canadian swine herds between 2016 and 2020 were tested for rotaviruses A, B, and C using a real-time polymerase-chain reaction assay and described. Data from Ontario and Quebec were additionally analyzed using boxplots, 6-week rolling averages, time-series decomposition, and negative binomial regression models. Percentage positivity of submissions for rotaviruses A, B, and C were discovered to be highest in nursery/weaner (n = 100, 94.0%, 60.0%, 80.0%) and grower/finisher (n = 13, 84.6%, 46.2%, 61.5%) pigs and lowest in gilt/sow (n = 45, 68.9%, 20.0%, 40.0%) and suckling pigs (n = 102, 67.6%, 10.8%, 38.2%), respectively. The most common combination of rotavirus at the sample level was AC (n = 252, 17%) and ABC (n = 175, 23.2%) at the submission level. Percent positivity for rotavirus A, B, and C across all Canadian provinces included in the study were 69.9%, 32.6%, and 53.1%, respectively. Descriptive analysis suggested little to no evidence of seasonal patterns, although a spike in November was seen in the monthly total submissions and monthly total positive submissions. Statistically, the overall month effect could not be identified as statistically significant (P > 0.05) for any of the evaluated submission counts. Overall, there was no evidence supporting seasonality of rotavirus within Ontario and Quebec swine herds between 2016 and 2020.

Rotavirus Infection in Swine: Genotypic Diversity, Immune Responses, and Role of Gut Microbiome in Rotavirus Immunity

Rotaviruses (RVs) are endemic in swine populations, and all swine herds certainly have a history of RV infection and circulation. Rotavirus A (RVA) and C (RVC) are the most common among all RV species reported in swine. RVA was considered most prevalent and pathogenic in swine; however, RVC has been emerging as a significant cause of enteritis in newborn piglets. RV eradication from swine herds is not practically achievable, hence producers’ mainly focus on minimizing the production impact of RV infections by reducing mortality and diarrhea. Since no intra-uterine passage of immunoglobulins occur in swine during gestation, newborn piglets are highly susceptible to RV infection at birth. Boosting lactogenic immunity in gilts by using vaccines and natural planned exposure (NPE) is currently the only way to prevent RV infections in piglets. RVs are highly diverse and multiple RV species have been reported from swine, which also contributes to the difficulties in preventing RV diarrhea in swine herds. Human RV-gut microbiome studies support a link between microbiome composition and oral RV immunogenicity. Such information is completely lacking for RVs in swine. It is not known how RV infection affects the functionality or structure of gut microbiome in swine. In this review, we provide a detailed overview of genotypic diversity of swine RVs, host-ranges, innate and adaptive immune responses to RVs, homotypic and heterotypic immunity to RVs, current methods used for RV management in swine herds, role of maternal immunity in piglet protection, and prospects of investigating swine gut microbiota in providing immunity against rotaviruses.

Milk lactose protects against porcine group A rotavirus infection

Rotavirus A (RVA) is an important pathogen causing acute gastroenteritis in animals and humans. Attachment to the host receptor is a crucial step for virus replication. The VP8* domain is the distal terminal region of the RVA spike protein VP4 (expressed by the P gene) and is important for rotavirus binding and infectivity. Recent studies have indicated a role for non-sialylated glycans, including mucin core 2 and histo-blood group antigens (HBGAs), in the infectivity of human and animal group A rotaviruses. In the present study, we determined if porcine rotavirus-derived recombinant VP8* of the endemic strains 14R103 G5P[6], 13R054 G5P[7], 12R010 G4P[13], 12R046 G9P[23], and 12R022 G2P[27] interact with hitherto uncharacterized glycans. We successfully produced five recombinant GST-VP8* proteins of genotype P[6], P[7], P[13], P[23], and P[27]. The hemagglutination assay showed genotypes P[7] and P[23] hemagglutinate porcine and human red blood cells. In an array screen of > 300 glycans, recombinant VP8* of rotavirus genotype P[6], P[7], and P[13] showed specific binding to glycans with a Gal-β-1,4-Glc (β-lactose) motif, which forms the core structure of HBGAs. The specificity of glycan-binding was confirmed through an ELISA-based oligosaccharide binding assay. Further, 13R054 G5P[7] and 12R046 G9P[23] infectivity was significantly reduced by β-lactose in MA104 cells and primary porcine enterocytes. These data suggest that lactose, the main natural sugar in milk, plays an important role in protecting piglets from enteric viral replication and diarrhea.

Antiviral Activity of Porcine IFN-λ3 and IFN-α against Porcine Rotavirus In Vitro

Interferons (IFNs) play a major role in the host’s antiviral innate immunity. In response to viral infection, IFNs bind their receptors and initiate a signaling cascade, leading to the accurate transcriptional regulation of hundreds of IFN-stimulated genes (ISGs). Porcine rotavirus (PoRV) belongs to genus Rotavirus of the Reoviridae family; the infection is a global epidemic disease and a major threat to the pig industry. In this study, we found that IFN-λ3 inhibited the replication of PoRV in both MA104 cells and IPEC-J2 cells, and this inhibition was dose-dependent. Furthermore, the antiviral activity of IFN-λ3 was more potent in IPEC-J2 cells than in MA104 cells. Further research showed that IFN-λ3 and IFN-α might inhibit PoRV infection by activating ISGs, i.e., MxA, OASL and ISG15, in IPEC-J2 cells. However, the co-treatment of IFN-λ3 and IFN-α did not enhance the antiviral activity. Our data demonstrated that IFN-λ3 had antiviral activity against PoRV and may serve as a useful antiviral candidate against PoRV, as well as other viruses in swine.

Assessing the Epidemiology of Rotavirus A, B, C and H in Diarrheic Pigs of Different Ages in Northern Italy

Rotaviruses are classified in 10 groups (A to J), where rotavirus A (RVA) is the major cause of diarrhea in humans and animals. With some exceptions, there is scarce information on the epidemiology of non-A rotaviruses in human and animal hosts. Currently, five species (A, B, C, E and H) have been identified in pigs. In the present study we investigated the prevalence of RVA, RVB, RVC and RVH among diarrheic pigs of different ages, in different seasons and in the presence of co-infections. Two molecular assays were developed for the detection of porcine RVA, RVB, RVC and RVH and were used to screen 962 stool specimens from suckling, weaning and fattening pigs with acute enteritis. Overall, rotaviruses were detected in a high percentage of samples (78%), with RVA being predominant (53%), followed by RVC (45%), RVB (43%) and RVH (14%). RVA was more common in the suckling (58%) and weaning cohorts (64%), while RVB, RVC and RVH were also frequently detected in fattening pigs. Only RVA and RVB infections followed a seasonal trend and exhibited age-related differences. Rotavirus infections were frequently present in combination with other pathogens. The present study depicts a portrait of rich rotavirus diversity in porcine herds, identifying seasonal and age-related patterns of circulation of the different rotavirus species in the surveyed areas.

Study on the Utilization of Inpatient Services for Middle-Aged and Elderly Rural Females in Less Developed Regions of China

The aim of this study is to understand the utilization of inpatient services and its contributing factors among middle-aged and elderly females (MAEF) in less developed rural regions. Five surveys were conducted between 2006 and 2014 with rural residents of Jiangxi by stratified cluster random sampling. Participant females included only those who were aged 45 and above. Complex sampling logistics analysis was performed to analyze the effect of three factors on inpatient service. Complex sampling logistics regression analysis revealed that the probability of hospitalization for the divorced or widowed females was significantly lower than that of married ones (aOR = 0.177, p < 0.05). However, the probability of early discharge was significantly higher among divorced or widowed females than married ones (aOR = 3.237, p < 0.05). In addition, females with chronic diseases were more likely to be hospitalized (aOR = 3.682, p < 0.05). Also, early discharge (aOR = 7.689, p < 0.05) occurred among the participants who should be hospitalized but were not hospitalized occurred (aOR = 3.258, p < 0.05). The continuous improvement of the new rural cooperative medical policy has promoted the utilization of inpatient services for the MAEF. Findings from this study emphasize the need to strengthen the prevention and treatment of chronic diseases among middle-aged and elderly women.

Evolution of rotavirus C in humans and several domestic animal species

Rotavirus C (RVC) causes enteric disease in multiple species, including humans, swine, bovines, and canines. To date, the evolutionary relationships of RVC populations circulating in different host species are poorly understood, owing to the low availability of genetic sequence data. To address this gap, we sequenced 45 RVC complete genomes from swine samples collected in the United States and Mexico. A phylogenetic analysis of each genome segment indicates that RVC populations have been evolving independently in human, swine, canine, and bovine hosts for at least the last century, with inter-species transmission events occurring deep in the phylogenetic tree, and none in the last 100 years. Bovine and canine RVC populations clustered together nine of the 11 gene segments, indicating a shared common ancestor centuries ago. The evolutionary relationships of RVC in humans and swine were more complex, due to the extensive genetic diversity and multiple RVC clades identified in pigs, which were not structured geographically. Topological differences between trees inferred for different genome segments occurred frequently, including at nodes deep in the tree, indicating that RVC's evolutionary history includes multiple reassortment events that occurred a long time ago. Overall, we find that RVC is evolving within host-defined lineages, but the evolutionary history of RVC is more complex than previously recognized due to the high genetic diversity of RVC in swine, with a common ancestor dating back centuries. Pigs may act as a reservoir host for RVC, and a source of the lineages identified in other species, including humans, but additional sequencing is needed to understand the full diversity of this understudied pathogen across multiple host species.

Multilevel Analysis of Individual, Organizational, and Regional Factors Associated With Patient Safety Culture: A Cross-Sectional Study of Maternal and Child Health Institutions in China

Supplemental digital content is available in the text.

The aim of this study was to assess patient safety culture (PSC) in maternal and child health (MCH) institutions in China and its individual, organizational, and regional variations.

In situ hybridization detection and subtyping of rotaviruses in swine samples

Rotavirus groups A, B, and C (RVA, RVB, and RVC, respectively) have been the most prevalent and pathogenic in pigs. To date, immunohistochemistry is only available for RVA because of the lack of commercial antibodies for RVB and RVC. We developed a novel in situ hybridization RNA-based chromogenic technique (ISH-RNA) to detect and subtype RVA, RVB, and RVC. We evaluated 33 samples that were reverse-transcription PCR positive for RVA, RVB, and/or RVC. ISH-RNA was able to detect as few as 10³ RV RNA copies/mL. The new ISH-RNA test can be useful for routine investigation of rotavirus enteritis in order to guide strategies for control of the infection in pigs, but a full validation study needs to be completed. Pathogenesis studies may be conducted using ISH-RNA based on the identification of replicating virus.

Evaluation on the efficacy and immunogenicity of recombinant DNA plasmids expressing S gene from porcine epidemic diarrhea virus and VP7 gene from porcine rotavirus

Porcine rotavirus (PoRV) and porcine epidemic diarrhea virus (PEDV) usually co-infect pigs in modern large-scale piggery, which both can cause severe diarrhea in newborn piglets and lead to significant economic losses to the pig industry. The VP7 protein is the main coat protein of PoRV, and the S protein is the main structural protein of PEDV, which are capable of inducing neutralizing antibodies in vivo. In this study, a DNA vaccine pPI-2.EGFP.VP7.S co-expressing VP7 protein of PoRV and S protein of PEDV was constructed. Six 8-week-old mice were immunized with the recombinant plasmid pPI-2.EGFP.VP7.S. The high humoral immune responses (virus specific antibody) and cellular immune responses (IFN-γ, IL-4, and spleen lymphocyte proliferation) were evaluated. The immune effect through intramuscular injection increased with plasmid dose when compared with subcutaneous injection. The immune-enhancing effect of IFN-α adjuvant was excellent compared with pig spleen transfer factor and IL-12 adjuvant. These results demonstrated that pPI-2.EGFP.VP7.S possess the immunological functions of the VP7 proteins of PoRV and S proteins of PEDV, indicating that pPI-2.EGFP.VP7.S is a candidate vaccine for porcine rotaviral infection (PoR) and porcine epidemic diarrhea (PED).

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.

Longitudinal Surveillance of Porcine Rotavirus B Strains from the United States and Canada and In Silico Identification of Antigenically Important Sites

Rotavirus B (RVB) is an important swine pathogen, but control and prevention strategies are limited without an available vaccine. To develop a subunit RVB vaccine with maximal effect, we characterized the amino acid sequence variability and predicted antigenicity of RVB viral protein 7 (VP7), a major neutralizing antibody target, from clinically infected pigs in the United States and Canada. We identified genotype-specific antigenic sites that may be antibody neutralization targets. While some antigenic sites had high amino acid functional group diversity, nine antigenic sites were completely conserved. Analysis of nucleotide substitution rates at amino acid sites (dN/dS) suggested that negative selection appeared to be playing a larger role in the evolution of the identified antigenic sites when compared to positive selection, and was identified in six of the nine conserved antigenic sites. These results identified important characteristics of RVB VP7 variability and evolution and suggest antigenic residues on RVB VP7 that are negatively selected and highly conserved may be good candidate regions to include in a subunit vaccine design due to their tendency to remain stable.

Porcine Rotaviruses: Epidemiology, Immune Responses and Control Strategies

Rotaviruses (RVs) are a major cause of acute viral gastroenteritis in young animals and children worldwide. Immunocompetent adults of different species become resistant to clinical disease due to post-infection immunity, immune system maturation and gut physiological changes. Of the 9 RV genogroups (A–I), RV A, B, and C (RVA, RVB, and RVC, respectively) are associated with diarrhea in piglets. Although discovered decades ago, porcine genogroup E RVs (RVE) are uncommon and their pathogenesis is not studied well. The presence of porcine RV H (RVH), a newly defined distinct genogroup, was recently confirmed in diarrheic pigs in Japan, Brazil, and the US. The complex epidemiology, pathogenicity and high genetic diversity of porcine RVAs are widely recognized and well-studied. More recent data show a significant genetic diversity based on the VP7 gene analysis of RVB and C strains in pigs. In this review, we will summarize previous and recent research to provide insights on historic and current prevalence and genetic diversity of porcine RVs in different geographic regions and production systems. We will also provide a brief overview of immune responses to porcine RVs, available control strategies and zoonotic potential of different RV genotypes. An improved understanding of the above parameters may lead to the development of more optimal strategies to manage RV diarrheal disease in swine and humans.