Isolation of rhinovirus from cattle in outbreaks of acute respiratory disease

Detection and Genomic Characterization of Bovine Rhinitis Virus in China

Bovine rhinitis virus (BRV) is an etiological agent of bovine respiratory disease complex (BRDC) and can be divided into two genotypes-bovine rhinitis A virus (BRAV) and bovine rhinitis B virus (BRBV). However, knowledge about the prevalence and molecular information of BRV in China is still limited. In this study, 163 deep nasal swabs collected from bovines with BRDC syndrome on 16 farms across nine provinces of China were tested for BRAV and BRBV by a duplex real-time RT-PCR assay. The results showed that 28.22% (46/163) of the samples were BRV-positive, and the positive rates were 22.09% (36/163) for BRAV and 9.2% (15/163) for BRBV. The co-circulation of both BRV genotypes was observed on two farms. Furthermore, five near-complete BRV genomes, including three BRAVs and two BRBVs, were obtained. The phylogenetic analysis showed that the three obtained BRAVs were phylogenetically independent, while the two BRBVs exhibited significant genetic heterogeneity. Recombination analysis revealed that three BRAVs and one BRBV strain obtained in this study were recombinants. The present study confirmed the presence and prevalence of BRAV in China, and it found that both types of BRV are circulating in beef cattle, which contributes to a better understanding of the prevalence and molecular characteristics of BRV.

Bovine rhinitis B virus is highly prevalent in acute bovine respiratory disease and causes upper respiratory tract infection in calves

Bovine respiratory disease (BRD) is the most significant cause of cattle morbidity and mortality worldwide. This multifactorial disease has a complex aetiology. Dogma posits a primary viral infection followed by secondary bacterial pneumonia. Bovine rhinitis B virus (BRBV) is an established aetiological agent of BRD, but little is known regarding its pathogenesis. Here, a BRD PCR panel identified 18/153 (11.8 %) lung samples and 20/49 (40.8 %) nasal swabs collected from cattle with respiratory signs as positive for BRBV, which was the most prevalent virus in nasal swabs. Primary bovine tracheal epithelial cells were used to isolate BRBV that was phylogenetically related to contemporary sequences from the USA and Mexico and genetically divergent from the previous sole BRBV isolate. To investigate virus pathogenesis, 1-week-old colostrum-deprived dairy calves were inoculated intranasally with 7.0 log₁₀ TCID₅₀ BRBV. Virus was isolated from nasal swabs, nasal turbinates, trachea and the brain of the challenged animals. Neutralizing antibodies were detected beginning 7 days post-inoculation and peaked at day 14. In situ hybridization (ISH) localized BRBV infection in the upper respiratory ciliated epithelial and goblet cells, occasionally associated with small defects of the superficial cilia lining. Sporadically, pinpoint ISH signals were also detected in cells resembling glial cells in the cerebrum in one calf. Together, these results demonstrate the BRBV infection is highly prevalent in acute BRD samples and while the pathogenicity of BRBV is minimal with infection largely limited to the upper respiratory tract, further research is needed to elucidate a possible initiatory role in BRD.

Bovine rhinitis viruses are common in U.S. cattle with bovine respiratory disease

Bovine rhinitis viruses (BRV) are established etiological agents of bovine respiratory disease complex however little research into their epidemiology and ecology has been published for several decades. In the U.S., only bovine rhinitis A virus 1 (BRAV1) has been identified while bovine rhinitis A virus 2 (BRAV2) and bovine rhinitis B virus (BRBV) were previously only identified in England and Japan, respectively. Metagenomic sequencing of a nasal swab from a bovine respiratory disease (BRD) diagnostic submission from Kansas identified contigs with approximately 90% nucleotide similarity to BRAV2 and BRBV. A combination of de novo and templated assemblies using reference genomes yielded near complete BRAV2 and BRBV genomes. The near complete genome of bovine rhinitis A virus 1 (BRAV1) was also determined from a historical isolate to enable further molecular epidemiological studies. A 5’-nuclease reverse transcription PCR assay targeting the 3D polymerase gene was designed and used to screen 204 archived BRD clinical specimens. Thirteen (6.4%) were positive. Metagenomic sequencing of six positive samples identified mixed BRAV1/BRAV2, BRAV1/BRBV and BRAV2/BRBV infections for five samples. One sample showed infection only with BRAV1. Seroprevalence studies using a cell culture adapted BRBV found immunofluorescence assay-reactive antibodies were common in the herds analyzed. Altogether, these results demonstrate that BRV infections are common in cattle with respiratory disease and that BRAV1, BRAV2 and BRBV co-circulate in U.S. cattle and have high similarity to viruses isolated more than 30 years ago from diverse locations.

Development and application of one-step multiplex reverse transcription PCR for simultaneous detection of five diarrheal viruses in adult cattle

A one-step multiplex reverse transcription (RT)-PCR method was developed for the simultaneous detection of five viruses causing diarrhea in adult cattle: bovine group A rotavirus (GAR), bovine group B rotavirus (GBR), bovine group C rotavirus (GCR), bovine coronavirus (BCV), and bovine torovirus (BToV). The detection limit of the one-step multiplex RT-PCR for GAR, GCR, BCV, and BToV was 10², 10⁰, 10¹, and 10² TCID₅₀/ml, respectively, and that for GBR was 10⁶ copies/ml. The one-step multiplex RT-PCR with newly designed primers to detect GAR had higher sensitivity than a single RT-PCR with conventional primers, with no false-positive reactions observed for ten other kinds of bovine RNA viruses To assess its field applicability, 59 of 60 fecal samples containing one of these five viruses from all 25 epidemic diarrhea outbreaks in adult cattle were positive in the one-step multiplex RT-PCR assay. Furthermore, using four additional fecal samples containing two viruses (GBR and BCV or BToV), two amplified products of the expected sizes were obtained simultaneously. In contrast, all 80 fecal samples lacking the five target viruses from normal adult cattle were negative in the multiplex assay. Taken together, our results indicate that the one-step multiplex RT-PCR developed here for the detection of GAR, GBR, GCR, BCV, and BToV can be expected to be a useful tool for the rapid and cost-effective diagnosis and surveillance of viral diarrhea in adult cattle.

Isolation of a new serotype of bovine rhinovirus from cattle. Brief report

Six strains of a new serological type of bovine rhinovirus were isolated in primary calf kidney cell cultures from nasal swab specimens of cattle with acute respiratory disease in Japan. They are serologically indistinguishable from one another and show no cross reaction with bovine rhinovirus types 1 and 2. We propose that the new isolates classified as bovine rhinovirus serotype 3.