Enteric Viral Infections among Domesticated South American Camelids: First Detection of Mammalian Orthoreovirus in Camelids

First Specific Detection of Mammalian Orthoreovirus from Goats Using TaqMan Real-Time RT-PCR Technology

Mammalian orthoreovirus (MRV) infections are ubiquitous in multiple mammalian species including humans, and mainly causes gastroenteritis and respiratory disease. In this study, we developed a rapid and sensitive TaqMan qRT-PCR method for MRV detection based on the primers and probe designed within the conserved L1 gene. The qRT-PCR assay was evaluated for its sensitivity, specificity, efficiency and reproducibility. It was found that the detection sensitivity was equivalent to 10 DNA copies/μL, and the standard curves had a linear correlation of R2 = 0.998 with an amplification efficiency of 99.6%. The inter- and intra-assay coefficients of variation (CV%) were in the range of 0.29% to 2.16% and 1.60% to 3.60%, respectively. The primer sets specifically amplified their respective MRV segments and had the highest detection sensitivities of 100.25 TCID50/mL with amplification efficiencies of 99.5% (R2 = 0.999). qRT-PCR was used for MRV detection from samples of sheep, goats, and calves from four regions in China, and the overall MRV prevalence was 8.2% (35/429), whereas 17/429 (4.0%) were detected by RT-PCR and 14/429 (3.3%) by virus isolation. The qRT-PCR assay showed significantly higher sensitivity than RT-PCR and virus isolation. Results from an epidemiological survey indicated that the positive rate of MRV in rectal swabs from sheep and goats tested in Shaanxi, Jiangsu, and Xinjiang were 9/80 (11.3%), 12/93 (12.9%) and 14/128 (10.9%), respectively. In goats and sheep, MRV prevalence was obviously associated with season and age, with a high positive rate of more than 8% during September to April and approximately 13% in small ruminant animals under two months of age. This is the first instance of MRV infection in sheep and goats in China, thus broadening our knowledge of MRV hosts. Consequently, primer optimization for qRT-PCR should not only prioritize amplification efficiency and specificity, but also sensitivity. This assay will contribute to more accurate and rapid MRV monitoring by epidemiological investigation, viral load, and vaccination efficacy.

Co-Circulation of Multiple Coronavirus Genera and Subgenera during an Epizootic of Lethal Respiratory Disease in Newborn Alpacas (Vicugna pacos) in Peru: First Report of Bat-like Coronaviruses in Alpacas

Coronaviruses (CoVs) infect a wide range of hosts, including humans, domestic animals, and wildlife, typically causing mild-to-severe respiratory or enteric disease. The main objective of this study was to identify CoV genera and subgenera detected in Peruvian alpacas. Lung lavage specimens were collected from 32 animals aged 1 to 6 weeks. CoVs were identified by using RT-PCR to amplify a pan-CoV conserved region of the RNA-dependent RNA polymerase-encoding gene. A nested PCR was performed to identify β-CoVs. Then, β-CoV-positive samples were subjected to RT-PCR using specific primers to identify the Embecovirus subgenus. Out of 32 analyzed samples, 30 (93.8%) tested positive for at least one CoV genus. β-, α-, or unclassified CoVs were identified in 24 (80%), 1 (3.3%), and 1 (3.3%) of the positive samples, respectively. A CoV genus could not be identified in two (6.7%) samples. A mixture of different CoV genera was detected in two (6.7%) samples: one was co-infected with β- and α-CoVs, and the other contained a β- and an unclassified CoV. A sequence analysis of the amplicons generated by the PCR identified 17 β-CoV strains belonging to the subgenus Embecovirus and two α-CoV strains belonging to Decacovirus. A phylogenetic analysis of two strains revealed a relationship with an unclassified Megaderma BatCoV strain. A subgenus could not be identified in nine β-CoV samples. Our data show a high prevalence and a high genetic diversity of CoV genera and subgenera that infect alpacas, in which the β-CoV subgenus Embecovirus predominated. Our data also suggest a new role for bats in the dissemination and transmission of uncommon CoVs to alpacas raised in rural Peru.

SARS-CoV-2 prevalence in domestic and wildlife animals: A genomic and docking based structural comprehensive review

The SARS-CoV-2 virus has been identified as the infectious agent that led to the COVID-19 pandemic, which the world has seen very recently. Researchers have linked the SARS-CoV-2 outbreak to bats for the zoonotic spread of the virus to humans. Coronaviruses have a crown-like shape and positive-sense RNA nucleic acid. It attaches its spike glycoprotein to the host angiotensin-converting enzyme 2 (ACE2) receptor. Coronavirus genome comprises 14 ORFs and 27 proteins, spike glycoprotein being one of the most critical proteins for viral pathogenesis. Many mammals and reptiles, including bats, pangolins, ferrets, snakes, and turtles, serve as the principal reservoirs for this virus. But many experimental investigations have shown that certain domestic animals, including pigs, chickens, dogs, cats, and others, may also be able to harbor this virus, whether they exhibit any symptoms. These animals act as reservoirs for SARS-CoV, facilitating its zoonotic cross-species transmission to other species, including humans. In this review, we performed a phylogenetic analysis with multiple sequence alignment and pairwise evolutionary distance analysis, which revealed the similarity of ACE2 receptors in humans, chimpanzees, domestic rabbits, house mice, and golden hamsters. Pairwise RMSD analysis of the spike protein from some commonly reported SARS-CoV revealed that bat and pangolin coronavirus shared the highest structural similarity with human coronavirus. In a further experiment, molecular docking confirmed a higher affinity of pig, bat, and pangolin coronavirus spike proteins' affinity to the human ACE2 receptor. Such comprehensive structural and genomic analysis can help us to forecast the next likely animal source of these coronaviruses that may infect humans. To combat these zoonotic illnesses, we need a one health strategy that considers the well-being of people and animals and the local ecosystem.

Genetic diversity, reassortment, and recombination of mammalian orthoreoviruses from Japanese porcine fecal samples

Mammalian orthoreoviruses (MRVs) are non-enveloped double-stranded RNA viruses with a broad host range. MRVs are prevalent worldwide, and in Japan, they have been isolated from various hosts, including humans, dogs, cats, wild boars, and pigs, and they have also been found in sewage. However, Japanese porcine MRVs have not been genetically characterized. While investigating porcine enteric viruses including MRV, five MRVs were isolated from the feces of Japanese pigs using MA104 cell culture. Genetic analysis of the S1 gene revealed that the Japanese porcine MRV isolates could be classified as MRV-2 and MRV-3. Whole genome analysis showed that Japanese porcine MRVs exhibited genetic diversity, although they shared sequence similarity with porcine MRV sequences in the DDBJ/EMBL/GenBank database. Several potential intragenetic reassortment events were detected among MRV strains from pigs, sewage, and humans in Japan, suggesting zoonotic transmission. Furthermore, homologous recombination events were identified in the M1 and S1 genes of Japanese porcine MRV. These findings imply that different strains of Japanese porcine MRV share a porcine MRV genomic backbone and have evolved through intragenetic reassortment and homologous recombination events.