Analysis of the VP6 gene of human and porcine group A rotavirus strains with unusual subgroup specificities

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.

Whole-genomic analysis of 12 porcine group A rotaviruses isolated from symptomatic piglets in Brazil during the years of 2012-2013

Group A rotaviruses (RVAs) are leading causes of viral diarrhea in children and in the young of many animal species, particularly swine. In the current study, porcine RVAs were found in fecal specimens from symptomatic piglets on 4 farms in Brazil during the years of 2012-2013. Using RT-PCR, Sanger nucleotide sequencing, and phylogenetic analyses, the whole genomes of 12 Brazilian porcine RVA strains were analyzed. Specifically, the full-length open reading frame (ORF) sequences were determined for the NSP2-, NSP3-, and VP6-coding genes, and partial ORF sequences were determined for the VP1-, VP2-, VP3-, VP4-, VP7-, NSP1-, NSP4-, and NSP5/6-coding genes. The results indicate that all 12 strains had an overall porcine-RVA-like backbone with most segments being designated as genotype 1, with the exception of the VP6- and NSP1-coding genes, which were genotypes I5 and A8, respectively. These results add to our growing understanding of porcine RVA genetic diversity and will provide a platform for monitoring the role of animals as genetic reservoirs of emerging human RVAs strains.

Whole-genomic analysis of rotavirus strains: current status and future prospects

Studies on genetic diversity of rotaviruses have been primarily based on the genes encoding the antigenically significant VP7 and VP4 proteins. Since the rotavirus genome has 11 segments of RNA that are vulnerable to reassortment events, analyses of the VP7 and VP4 genes may not be sufficient to obtain conclusive data on the overall genetic diversity, or true origin of strains. In the last few years following the advent of the whole-genome-based genotype classification system, the whole genomes of at least 167 human group A rotavirus strains have been analyzed, providing a plethora of new and important information on the complex origin of strains, inter- and intra-genogroup reassortment events, animal–human reassortment events, zoonosis, and genetic linkages involving different group A rotavirus gene segments. In addition, the whole genomes of a limited number of human group B, C and novel group rotavirus strains have been analyzed. This article briefly reviews the available data on whole-genomic analysis of human rotavirus strains. The significance and future prospects of whole-genome-based studies are also discussed.

A novel multiplex RT-PCR for identification of VP6 subgroups of human and porcine rotaviruses

VP6 protein antigens allow classification of rotaviruses into at least four subgroups, depending on the presence or absence of SG-specific epitopes: SG I, SG II, SG (I+II), and SG non-(I+II). However, MAbs against epitopes on the VP6 protein of human and porcine rotaviruses, sometimes, do not recognize SG-specific epitopes or recognize irrelevant-SG epitopes and therefore result in the incorrect assignment of subgroups. In order to solve this problem, a novel multiplex RT-PCR was developed as an alternative tool to identify VP6 genogroups using newly designed primers which are specific for genogroup I or II. The sensitivity and specificity of the newly developed multiplex RT-PCR method was evaluated by testing with human and porcine rotaviruses of known SG I, SG II, SG (I+II), and SG non-(I+II) strains in comparison with monoplex RT-PCR and VP6 sequence analysis. The results show that the genogroups of both human and porcine rotaviruses as determined by the new multiplex RT-PCR method were in 100% agreement with those determined by monoplex RT-PCR and VP6 sequence analysis. The method was shown to be specific, sensitive, less-time consuming, and successful in genogrouping clinical isolates of rotaviruses circulating in children and piglets with acute diarrhea.