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

Development of a 1-step TaqMan real-time PCR method for detection of the Bovine Group A Rotavirus

BACKGROUND

The purpose of this study was to develop a 1-step real-time quantitative fluorescence polymerase chain reaction (QF-PCR) method for detecting Bovine Group A Rotavirus (BRVA). The primers and probe were designed targeting the VP6 gene of BRVA. The standard substance was obtained through in vitro transcription. The primers, probe concentration, and annealing temperatures were optimized to determine the optimal system and conditions for the reaction. The specificity, sensitivity, and repeatability of the method were assessed and compared with a reported real-time QF-PCR method for clinical samples.

RESULTS

The results indicated that the detection method can achieve a sensitivity of 3.47 copies/μL and exhibit good specificity by exclusively detecting BRVA without cross-reactivity to other common pathogens in cattle and sheep. The standard curve exhibited a robust linear correlation, and the amplification efficiency was calculated to be 105%. The intra-group and inter-group coefficients of variation were less than 2%. A total of 96 clinical samples were tested and compared with the real-time QF-PCR method that was reported. The coincidence rate was 90.63% (87/96). Furthermore, the clinical samples revealed that the prevalence of BRV in cattle from Fujian Province was 85.42% (82/96).

CONCLUSION

This study has successfully developed a 1-step real-time QF-PCR method for BRVA, which offers an efficient and sensitive technical support for the rapid diagnosis and epidemiological investigation of BRVA.

Phylogenetic Analysis of G and P Genotypes of Bovine Group A Rotavirus Strains Isolated from Diarrheic Vietnam Cows in 2017 and 2018

This study aimed to investigate the genetic diversity of G- and P-type bovine RVAs (BoRVAs) prevalent in Vietnam. Between 2017 and 2018, the prevalence of BoRVAs detected in diarrhea samples from 8 regions was as low as 1.9% (11/582). The prevalence of the G-type was 45.5% for G6 and 18.2% for G10; however, 36.3% remain unidentified. Interestingly, all BoRVAs were investigated as P[11], and there was no diversity within this P-type. Geographically, the G6 and G10 types were not identified in any specific area; rather, they occurred in both Northern and Southern Vietnam. G6P[11] and G10P[11], which are combined G- and P-types, were identified in 71.4% and 28.6% of BoRVA-positive samples, respectively. Phylogenetic tree analysis revealed that the G6-type detected in Vietnamese cows is similar to strains derived from China, Japan, and Korea, whereas the G10 type is closely related to the Chinese strain. In addition, the P11 strain detected in Vietnamese cows is similar to the Spanish and Chinese strains. The BoRVA-positive rate was higher in cows aged less than 2 months (3.2%, 3/94) than in those aged 2 months or more (1.6%, 8/488). In summary, we detected the presence of G6P11 and G10P11 BoVRAs on Vietnamese cow farms, and found that they were more predominant in young calves than in older cows.

Characterization of bovine rotavirus isolates from diarrheic calves in Türkiye

BACKGROUND

Neonatal calf diarrhea, which is the most common cause in calf deaths, leads to significant economic losses in dairy farming around the world. Diarrhea develops due to infectious and non-infectious reasons. Group A Rotaviruses (RVA) are the leading and predisposing factor for acute neonatal gastroenteritis.

METHODS AND RESULTS

In this study, 20 diarrheic fecal samples were collected from one farm in Balıkesir province of Turkey. During virus isolation, a total of 2 stool samples were detected to produce cytopathogenic effects in MA-104 cell line. The two samples (RV-36, RV-38) were tested positive with antigen ELISA kits detecting RVA antigens. In order to detect the presence of rotavirus viral nucleic acid in cell supernatants, VP6 gene region-specific RT-PCR test was performed and the samples RV-36 and RV-38 were positive for RVA viral nucleic acid. By RT-PCR using genotype specific primers, both the isolates RV-36 and RV-38 formed amplicons compatible with G10 and P[11] genotypes of RVA. RVA nucleic acids segments were also visualized by poliacrilamide gel electrophoresis (PAGE) method. The phylogenetic tree constructed according to the VP6 gene region showed that these isolates were in the Rotavirus A group and in the I2 cluster same as other bovine and some human RVA isolates.

CONCLUSION

Succesful isolation of RVA G10P[11] was echieved in the cattle farm. As rotaviruses play the most important role in the etiology of diarrhea in newborn calves respected genotype G10P[11] should be considered in selection of the vaccines applied to the dams. Those isolates can be further evaluated as vaccine candidate.

Detection of the dominant pathogens in diarrheal calves of Ningxia, China in 2021-2022

Introduction

Calf diarrhea is a complex disease that has long been an unsolved problem in the cattle industry. Ningxia is at the forefront of China in the scale of cattle breeding, and calf diarrhea gravely restricts the development of Ningxia's cattle industry.

Methods

From July 2021 to May 2022, we collected diarrhea stool samples from calves aged 1-103 days from 23 farms in five cities in Ningxia, and performed PCR using specific primers for 15 major reported pathogens of calf diarrhea, including bacteria, viruses, and parasites. The effect of different seasons on the occurrence of diarrhea in calves was explored, the respective epidemic pathogens in different seasons were screened, and more detailed epidemiological investigations were carried out in Yinchuan and Wuzhong. In addition, we analyzed the relationship between different ages, river distributions and pathogen prevalence.

Results

Eventually, 10 pathogens were detected, of which 9 pathogens were pathogenic and 1 pathogen was non-pathogenic. The pathogens with the highest detection rate were Cryptosporidium (50.46%), Bovine rotavirus (BRV) (23.18%), Escherichia coli (E. coli) K99 (20.00%), and Bovine coronavirus (BCoV) (11.82%). The remaining pathogens such as Coccidia (6.90%), Bovine Astrovirus (BoAstV) (5.46%), Bovine Torovirus (BToV) (4.09%), and Bovine Kobuvirus (BKoV) (3.18%) primarily existed in the form of mixed infection.

Discussion

The analysis showed that different cities in Ningxia have different pathogens responsible for diarrhea, with Cryptosporidium and BRV being the most important pathogens responsible for diarrhea in calves in all cities. Control measures against those pathogens should be enforced to effectively prevent diarrhea in calves in China.

Genetic Diversity of Bovine Group A Rotavirus Strains Circulating in Korean Calves during 2014 and 2018

The purpose of this study was to investigate annual changes in BoRVA strains by examining the VP4 and VP7 genes of rotaviruses in Korean calves. Between 2014 and 2018, 35 out of 138 samples of calf diarrhea feces collected nationwide were positive for BoRVA. Further genetic characterization of the VP7 and VP4 genes of 35 BoRVA isolates identified three different G-genotypes (G6, G8, and G10) and two different P genotypes (P[5] and P[11]). The G6 genotype was most common (94.3%) in BoRVA-positive calves, followed by the P[5] genotype (82.9%). Four genotypes comprised combinations of VP4 and VP7: 80% were G6P[5], 14.2% were G6P[11], 2.9% were G8P[5], and 2.9% were G10P[11]. Susceptibility to infection was highest in calves aged < 10 days (35%) and lowest in calves aged 30−50 days (15.4%). The data presented herein suggest that the G6P[5] genotype is the main causative agent of diarrhea in Korean calves. In addition, it is predicted that G6P[5] will continue to act as a major cause of diarrhea in Korean calves.

Prevalence of bovine rotavirus among Bovidae in China during 1984-2021: A systematic review and meta-analysis

Bovine rotavirus (BRV) is a potential zoonotic intestinal pathogen that brings a serious threat to calf health, and has resulted in huge economic losses to China's breeding industry. Here, a systematic review and meta-analysis was conducted to estimate the prevalence of BRV among Bovidae from 1984 to 2021 in China. A total of 64 publications on BRV investigation in China were screened from the databases Chinese National Knowledge Infrastructure (CNKI), Wan Fang Database, Technology Periodical Database (VIP), PubMed, and ScienceDirect. The random-effect model was used to calculate the pooled prevalence of BRV, and the analyzed data were derived from 25 provinces in China. The estimated pooled prevalence of BRV in China was 35.7% (8176/17,292). In addition, the prevalence of BRV in Southwestern China (77.1%; 2924/3600) was significantly higher than that in other regions of China. Regarding geographic and climatic factors, the prevalence of BRV in the subgroup of latitude 30-35° (76.8%; 3303/4659) was significantly higher than that in the subgroup of latitude less than 30° (37.0%; 485/1275) or more than 35° (32.6%; 1703/5722), while the prevalence of BRV in the subgroup of longitude 100-105° (75.4%; 2513/3849) was significantly higher than that in the subgroup of longitude less than 100° (32.6%; 619/2255) or more than 105° (48.9%; 2359/5552). Rainfall was positively correlated with the prevalence of BRV, whereas temperature was negatively correlated with the positive rate of BRV (P < 0.05). Our data showed that the prevalence of BRV was strongly correlated with geographical and climatic conditions. Thus, we recommend that the corresponding prevention and control programs should be formulated according to different geographical conditions. The strengthening of BRV surveillance in areas with high altitude, low temperature, and heavy rainfall may contribute to the decrease of the incidence of BRV infection among Bovidae herds in China.

Affinity Peptide-based Electrochemical Biosensor for the Highly Sensitive Detection of Bovine Rotavirus

Bovine diarrhea is a major concern in the global bovine industry because it can cause significant financial damage. Of the many potential infectious agents that can lead to bovine diarrhea, bovine rotavirus (BRV) is a particular problem due to its high transmissibility and infectivity. Therefore, it is important to prevent the proliferation of BRV using an early detection system. This study developed an affinity peptide-based electrochemical method for use as a rapid detection system for BRV. A BRV-specific peptide was identified via the phage display technique and chemically synthesized. The synthetic peptide was immobilized on a gold electrode through thiol-gold interactions. The performance of the BRV specific binding peptides was evaluated using square wave voltammetry. The developed detection system exhibited a low detection limit (5 copies/mL) and limit of quantitation (2.14 × 10² copies/mL), indicating that it is a promising sensor platform for the monitoring of BRV.

Isolation and Characterization of Bovine RVA from Northeast China, 2017-2020

Group A rotaviruses (RVAs) are major enteric pathogens causing infections in calves. To investigate the epidemiological characteristics and genetic diversity of bovine rotavirus (BRV), 233 fecal samples were collected from calves with diarrhea in northeast China. The samples were analyzed for sequences encoding the inner capsid protein VP6 (subgroup) and the outer capsid proteins VP7 and VP4 (G and P type, respectively) using RT-PCR. Ten of the 233 samples (4.3%) were identified as BRV positive and were used for virus isolation and sequence analysis, revealing that all strains analyzed were of the G6P[1] genotype. The isolates exhibited high VP6 sequence identity to the USA cow RVA NCDV strain (>99% amino acid identity) and were further shown to be closely related to Japanese cow RVA BRV101 and Israelian human RVA G6P[1] strains, with >99% amino acid identity to VP7 and VP4 proteins, respectively. Comparative analyses of genome-predicted amino acid sequences between the isolates and the NCDV strains indicated that the antigenicity and infectivity of the strains isolated had changed. In this study, BRV genotypes and the genetic diversity among vaccinated cattle herds were monitored to provide epidemiological data and references for early diagnosis, allowing for early detection of new, potentially pathogenic RVA strains.