The molecular epidemiology of bovine rotaviruses circulating in Iran: a two-year study

Efficient and robust reverse genetics system for bovine rotavirus generation and its application for antiviral screening

Unveiling the molecular mechanisms underlying rotavirus replication and pathogenesis has been hampered by the lack of a reverse genetics (RG) system in the past. Since 2017, multiple plasmid-based RG systems for simian, human, and murine-Like rotaviruses have been established. However, none of the described methods have supported the recovery of bovine rotaviruses (BRVs). Here, we established an optimized plasmid-based RG system for BRV culture-adapted strain (BRV G10P [15] BLR) and clinical isolates (BRV G6P[1] C73, G10P[11] HM26) based on a BHK-T7 cell clone stably expressing T7 polymerase. Furthermore, using this optimized RG system, we successfully rescued the reporter virus BRV rC73/Zs, rHM26/Zs and rBLR/Zs, harboring a genetically modified 1.8-kb segment 7 encoding full-length nonstructural protein 3 (NSP3) fused to ZsGreen, a 232-amino acid green fluorescent protein. Analysis of the stability of genomic insertions showed that the rC73/Zs and rBLR/Zs replicated efficiently and were genetically stable in seven rounds of serial passaging, while rHM26/Zs can be stabilized only up to the third generation, indicating that the BRV segment composition may influence the viral fitness. In addition, we adopted the recombinant reporter viruses for high-throughput screening application and discovered 12 candidates out of 1440 compounds with potential antiviral activities against rotavirus. In summary, this improved RG system of BRVs represents an important tool with great potential for understanding the molecular biology of BRV and facilitates the development of novel therapeutics and vaccines for BRV.

Prevalence of bovine rotavirus among cattle in mainland China: A meta-analysis

BACKGROUND

Bovine rotavirus is the primary pathogen causing diarrhea in cattle and can be transmitted vertically through the placenta. It mainly presents with clinical signs such as depression, loss of appetite, diarrhea, vomiting, and dehydration.

METHODS

A systematic review and meta-analysis were conducted to assess the prevalence of BRV infection in mainland China. We conducted a literature search on the prevalence of BRV infection in pigs between Jan 1, 1979 and Dec 31, 2021 in English and Chinese databases, including PubMed, Google Scholar, Cochrane library, Clinical Trials, VIP, CNKI, and WanFang database. Selections were made based on the title and the abstract of the paper, Search strings included if they reported the cattle samples of more than 15 cattle and provided information that allowed us to establish the prevalence of BRV. Moreover, we excluded repeated studies, reviews, other hosts. Finally, we extracted the number of cattle with BRV infection from the obtained studies and provided information that permitted us to estimate the prevalence of BRV infection in cattle in mainland China.

RESULTS

The data of 29 articles (including data on 10677 cattle) are compliant with the standards. The pooled prevalence of BRV in cattle in China was 46%（6635/10677）, the pooled prevalence of BRV in cattle from Northeast China (40%) was significantly lower than those from other regions. In addition, the prevalence of BRV was associated with publication time of paper, detection methods, age of cattle, and clinical symptoms（diarrhea, etc.).

CONCLUSION

Our findings suggest that BRV infection is common among cattle in China. It is, therefore, necessary to carry out further research and monitor the prevalence of BRV infection. Furthermore, powerful and effective regulatory measures should be taken to prevent the transmission and spread of BRV among cattle populations.

Molecular surveillance of rotavirus A associated with diarrheic calves from the Republic of Korea and full genomic characterization of bovine-porcine reassortant G5P[7] strain

Group A rotavirus (RVA) is the most common diarrhea-causing pathogen among humans and animals worldwide. Rotavirus infection in neonatal calves causes major problems in the livestock industry. This study aimed to determine the prevalence and genetic diversity of bovine rotavirus (BoRVA) infections in calves with diarrhea and to perform whole genome analysis of an unusual strain, designated as RVA/Calf-wt/KOR/KNU-GJ2/2020/G5P[7], that was detected in a 2-day-old diarrheic calf. From 459 diarrheic calves aged 1-40 days, fecal samples were collected and BoRVA infections were screened using real-time RT-PCR targeting VP6 gene. BoRVA was detected in 195 (42.4%) samples and was most prevalent in calves aged 1-10 days (47.2%). No significant difference in the BoRVA infection rate was observed between calves born in herds that were (42.1%) and were not (42.6%) vaccinated against BoRVA. A binomial regression analysis revealed that calves aged 1-10 days (95% confidence intervals [CI]:1.18-24.34; P = 0.000) and 11-20 days (95% CI: 0.76-16.83, P = 0.000) had a 5.37- and 3.58-fold higher BoRVA prevalence in comparison to those aged 31-40 days, respectively. The RVA-positive samples were subsequently subjected to amplification of the VP7 and VP4 genes for determining G and P genotypes. Overall, 45 (23.1%, 45/195) and 63 (32.3, 63/195) sequences for VP7 and VP4 were obtained. In this study, four G and three P genotypes were identified. G6 (86.7%) was the most prevalent genotype, followed by G8 (8.9%), G10 (2.2%), and G5 (2.2%). P[5] (92.1%) was the most frequently detected, followed by P[11] (6.3%), and P[7] (1.6%). The G6P[5] (82.2%) is the most common combination found in Korean native calves with diarrhea, whereas G6P[11] (4.4%) and G10P[11] (2.2%) had relatively low prevalence. G8P[5] (8.9%) was identified for the first time in diarrheic calves in the KOR. The uncommon strain KNU-GJ2 exhibited a G5-P[7]-I5-R1-C1-M2-A1-N1-T1-E1-H1 genotype constellation possessing a typical porcine RVA backbone, with the exception of the VP3 gene, which is derived from bovine. Phylogenetically, except for VP3, ten gene segments of KNU-GJ2 were closely related to porcine, porcine-like, and reassortant bovine strains. Interestingly, the VP3-M2 gene of KNU-GJ2 clustered with bovine-like strains as well as reassortant porcine and bovine strains. Comparison of the NSP4s within a species-specific region of amino acids 131-141 demonstrated that KNU-GJ2 belonged to genotype B with porcine RVAs; however, it differed from porcine RVAs by one to three amino acids. The present study is fundamental to understanding the epidemiology and genotypes of circulating RVAs throughout the KOR and underscoring the importance of continuous monitoring and molecular characterization of RVAs circulating within animal populations for future vaccine development.

Literature Review: Coinfection in Young Ruminant Livestock-Cryptosporidium spp. and Its Companions

The protozoan Cryptosporidium parvum is one of the major causative pathogens of diarrhoea in young ruminants; therefore, it causes economic losses and impairs animal welfare. Besides C. parvum, there are many other non-infectious and infectious factors, such as rotavirus, Escherichia coli, and Giardia duodenalis, which may lead to diarrhoeic disease in young livestock. Often, more than one infectious agent is detected in affected animals. Little is known about the interactions bet-ween simultaneously occurring pathogens and their potential effects on the course of disease. In this review, a brief overview about pathogens associated with diarrhoea in young ruminants is presented. Furthermore, information about coinfections involving Cryptosporidium is provided.

Detection and molecular characteristics of bovine rotavirus A in dairy calves in China

Background

Bovine group A rotavirus (BoRVA) is a major cause of severe gastroenteritis in newborn dairy calves. Only one study has investigated the G and P genotypes among dairy calves in a few regions of China, which were G6 and P[5]. Therefore, data on the prevalence and molecular characteristics of BoRVA in dairy calves in China remains limited.

Objectives

The purpose of this study was to investigate the prevalence and molecular characteristics of BoRVA in dairy calves in China.

Methods

269 dairy calves diarrheic samples from 23 farms in six provinces in China were collected to detect BoRVA using reverse transcription polymerase chain reaction.

Results

71% of samples were determined to be BoRVA-positive. Two G genotypes (G6, G10) and two P genotypes (P[1], P[5]) were identified, and G6P[1] BoRVA was the predominant strain. Moreover, the VP7 and VP4 gene sequences of these dairy calf BoRVA strains revealed abundant genetic diversity. Interestingly, eight out of 17 complete G6 VP7 sequences were clustered into G6 lineage VI and analysis showed the strains were closely related to Chinese yak BoRVA strains.

Conclusions

The results of this study show that BoRVA circulates widely among dairy calves in China, and the dominant genotype in circulation is G6P[1], first report on molecular characteristics of complete P[5] VP4 genes in chinese dairy calves. These results will help us to further understand the prevalence and genetic evolution of BoRVA among dairy calves in China and, thus, prevent the disease more effectively.

Cross-sectional study and genotyping of rotavirus-A infections in ruminants in Kuwait

Background

Group A rotaviruses (RVA) are zoonotic pathogens responsible for acute enteritis in human and neonatal ruminants. This research aimed to determine the prevalence of RVA in ruminants (cattle, sheep, and goats) and investigate the circulating RVA genotypes in these animals in Kuwait. We conducted a cross-sectional study to detect RVA in ruminants, using an immunochromatography test (IC), direct sandwich ELISA test, and real-time RT-PCR (RT-qPCR) assay using fecal samples.

Results

A total of 400 cattle, 334 sheep, and 222 goats were examined. The prevalence of RVA was 5.3, 1.2, and 2.3%, respectively, using IC. The ELISA test detected RVA from 4.3% of cattle, 0.9% of sheep, and 1.8% of goats. There was a significant association between the occurrence of diarrhea and the presence of RVA in bovine fecal samples (p-value = 0.0022), while no statistical association between diarrhea and the presence of RVA in fecal samples of sheep and goats was observed (p-value = 0.7250; p-value = 0.4499, respectively). Twenty-three of the IC-positive samples (17 from cattle, two from sheep, and four from goats) were tested using a RT-qPCR RVA detection assay targeting the NSP3 gene. The results showed that 21 of 23 IC-positive samples tested positive by RT-qPCR. Detection of RVA genotypes revealed that G10P[11] was the predominant strain in cattle (58.8%), followed by G8P[1] (11.7%). One sheep sample was genotyped as G8P[1]. In addition, G6P[1] and G6P[14] were detected in goat samples.

Conclusion

The present study revealed that the IC was more sensitive in detecting RVA antigen in fecal samples than the ELISA test. A higher occurrence of RVA infection was observed in cattle than in sheep and goats. This study suggests that RVA might be a risk factor of diarrhea in bovine calves less than 2 weeks old. This research also demonstrates the circulation of RVA in sheep and goat populations in Kuwait. Finally, the G10P[11] RVA genotype was the most prevalent genotype identified from cattle samples.

Supplementary Information

The online version contains supplementary material available at 10.1186/s12917-021-02944-4.

High prevalence and genomic characteristics of G6P[1] Bovine Rotavirus A in yak in China

Yak is an iconic species of the Qinghai-Tibet Plateau, which is the world's highest plateau. Here, a total of 541 yak diarrhoeic samples were collected from 69 farms in four provinces in the Qinghai-Tibet Plateau from April 2015 to June 2018, and 73.6 % of samples were detected as Bovine Rotavirus A (BRVA) positive by RT-PCR assay. Two G genotypes (G6, G10) and two P genotypes (P[1], P[11]) were determined, in which G6P[1] BRVA was the predominant strain. Moreover, VP7 and VP4 of these G6P[1] strains showed unique amino acid mutations, such that they clustered into an independent branch in the phylogenetic tree. A strain of BRVA designated as RVA/Yak-tc/CHN/QH-1/2015/G6P[1] was isolated successfully using MA104 cells, and the virus titre was determined as 10^5.84 TCID₅₀ ml^-1. The genome of strain QH-1 had a G6-P[1]-I2-R2-C2-M2-A3-N3-T6-E2-H3 genotype constellation. QH-1 was identified as a reassortment strain of BRVA, human RVA and ovine RVA based on the nucleotide identity and phylogenetic tree of 11 gene segments, indicating its public health significance. To the best of our knowledge, this is the first report on the molecular prevalence and genome characteristics of BRVA in yak, contributing to further understanding of the epidemic and genetic evolution of BRVA.

Occurrence and genetic diversity of rotavirus A in faeces of diarrheic calves submitted to a veterinary laboratory in Spain

A total of 237 faecal specimens from diarrheic calves younger than two months were collected and submitted for diagnosis of enteropathogens over a two-year period (2017-2018) to a veterinary laboratory. Samples originated from 193 dairy and beef farms in 29 provinces distributed throughout Spain, and were tested for the occurrence of three target enteric pathogens by reverse transcription real-time PCR (RT-qPCR): bovine rotavirus A (RVA), Cryptosporidium parvum and bovine coronavirus (BCoV). RT-PCR and nucleotide sequencing analysis were used to determine the G (VP7 gene) and P (VP4 gene) genotypes of 26 specimens positive for RVA. A total of 188 specimens (79.3 %) were positive for at least one of the three target enteric pathogens, and 101 samples (42.6 %) harbored mixed infections. The individual prevalence was 57.8 %, 50.6 % and 23.6 % for C. parvum, RVA and BCoV, respectively. Molecular analysis of selected RVA strains revealed the presence of the G6, G10, G3, P[5] and P[11] genotypes, with the combinations G6P[5] and G6P[11] being the most prevalent. Alignments of nucleotide sequences of the VP7 and VP4 markers showed a high frequency of single nucleotide polymorphisms (SNPs), with up to 294 SNPs found in 869bp of sequence at the G6 genotype (0.338 SNPs/nt), which reveals the extensive genetic diversity of RVA strains. Phylogenetic analysis of the VP7 gene of the G6 strains revealed four distinct lineages, with most strains clustering in the G6-IV lineage. The discrepancies between the RVA genotypes circulating in the sampled cattle farms and the genotypes contained in commercial vaccines currently available in Spain are discussed. We believe that this is the first study on the molecular characterization of rotavirus infecting cattle in Spain.

Phylogenetic Analyses of Rotavirus A from Cattle in Uruguay Reveal the Circulation of Common and Uncommon Genotypes and Suggest Interspecies Transmission

Uruguay is one of the main exporters of beef and dairy products, and cattle production is one of the main economic sectors in this country. Rotavirus A (RVA) is the main pathogen associated with neonatal calf diarrhea (NCD), a syndrome that leads to significant economic losses to the livestock industry. The aims of this study are to determine the frequency of RVA infections, and to analyze the genetic diversity of RVA strains in calves in Uruguay. A total of 833 samples from dairy and beef calves were analyzed through RT-qPCR and sequencing. RVA was detected in 57.0% of the samples. The frequency of detection was significantly higher in dairy (59.5%) than beef (28.4%) calves (p < 0.001), while it did not differ significantly among calves born in herds that were vaccinated (64.0%) or not vaccinated (66.7%) against NCD. The frequency of RVA detection and the viral load were significantly higher in samples from diarrheic (72.1%, 7.99 log₁₀ genome copies/mL of feces) than non-diarrheic (59.9%, 7.35 log₁₀ genome copies/mL of feces) calves (p < 0.005 and p = 0.007, respectively). The observed G-types (VP7) were G6 (77.6%), G10 (20.7%), and G24 (1.7%), while the P-types were P[5] (28.4%), P[11] (70.7%), and P[33] (0.9%). The G-type and P-type combinations were G6P[11] (40.4%), G6P[5] (38.6%), G10P[11] (19.3%), and the uncommon genotype G24P[33] (1.8%). VP6 and NSP1-5 genotyping were performed to better characterize some strains. The phylogenetic analyses suggested interspecies transmission, including transmission between animals and humans.

Molecular characterization of unusual G10P[33], G6P[14] genomic constellations of group A rotavirus and evidence of zooanthroponosis in bovines

Group A rotaviruses (RVA) are a major cause of diarrhea in neonatal calves and children. The present study examined G/P combinations and genetic characteristics of RVAs in diarrheic bovine calves in Western India. RVAs were detected in 27 samples (17.64%) with a predominance of G10P[11] (51.85%), followed by previously unreported genomic constellations, G6P[14] (14.81%), and, G6P[4] (7.40%) and G10P[33] (3.70%). Sequencing and phylogenetic analysis revealed circulation of G10 (Lineage-5), G6 (Lineage-2), P[11] (Lineage-3), P[14] (proposed Lineage-8) and P[4] (Lineage-3) genotypes. The predominant G10P[11] strains were typical bovine strains and exhibited genotypic homogeneity. The rare, G10P[33] strain, had VP7 and VP4 genes of bovine origin but, a resemblance of the VP6 gene with simian strain indicated possible reassortment between bovine and simian (SA11-like) strains. The VP6 and VP7 genes of two rare strains, G6P[14] and G6P[4], were identical to those of bovine stains, but the VP4 was closely related to those of the human-bovine like and human strains, respectively. Additionally, in the VP4 gene phylogenetic tree, Indian P[14] strains constituted a closely related genetic cluster distinct from the other P[14] strains. Hence Lineage-8 was proposed for them. These findings indicated that bovines could serve as a source for anthropozoonotic transmission of G6P[14] strains while zooanthroponotic transmission followed by reassortment with human strain gave rise to G6P[4] strains. The observations of a present study reinforce the potential of rotaviruses to cross the host-species barrier and undergo reassortant to increase genetic diversity which, necessitates their continuous surveillance for development and optimization of prevention strategies against zoonotic RVAs.

Vaccines the tugboat for prevention-based animal production

The world population is growing at a faster rate day-by-day and the demands for animal products are also increasing to meet the food security worldwide. For sustained production of animals products, healthy livestock and poultry farming are the major concerns as animals are susceptible to various infectious agents viz. bacteria, virus, and parasites leading to huge economical losses in the form of livestock’s morbidity and mortality. Besides, zoonotic nature of some infectious pathogens of animals is also raising concern for human safety. Vaccination of animals against various diseases present in different geographical regions is a best known strategy for prevention of different disease outbreaks both in organized and unorganized livestock and poultry sectors. Vaccines had played a major role in eradication of different dreaded diseases of livestock sectors globally. In this article we have discussed different vaccine types, various vaccine strategies used for the development of more efficacious and safe vaccines and commercially available vaccines for livestock and poultry.

Molecular prevalence of bovine noroviruses and neboviruses in newborn calves in Iran

In this study, bovine enteric caliciviruses (BECs) were detected in 49.4% of a total of 253 stool specimens for diarrheic calves collected from 42 industrial dairy farms from March 2010 to February 2012. Genogroup III norovirus (NoVsGIII) were more prevalent (39.5%) than neboviruses (NBs) (15%), and coinfections were observed in 5.1% of the samples tested. Sequence analysis of the partial polymerase gene from 13 NoVsGIII samples indicated the circulation of both genotype 1 and genotype 2 strains. Among the six NB strains sequenced, five were related to the Bo/Nebraska/80/US strain, while one was related to the Bo/Newbury1/76/UK strain.