Adaptation potential of H3N8 canine influenza virus in human respiratory cells.

In 2004, the equine-origin H3N8 canine influenza virus (CIV) first caused an outbreak with lethal cases in racing greyhounds in Florida, USA, and then spread to domestic dogs nationwide. Although transmission of this canine virus to humans has not been reported, it is important to evaluate its zoonotic potential because of the high contact opportunities between companion dogs and humans. To gain insight into the interspecies transmissibility of H3N8 CIV, we tested its adaptability to human respiratory A549 cells through successive passages.

Japanese Encephalitis Virus and Co-Infection in a Harbor Seal in Japan.

The Japanese encephalitis virus (JEV), a mosquito-borne flavivirus, has a wide host range, extending from pigs and ardeid birds to opportunistic dead-end hosts, such as humans and horses. However, JEV encephalitis infections in aquatic mammals are rare, with only two cases in seals reported to date. Here, we report a lethal case of JEV and co-infection in an aquarium-housed harbor seal in Japan.

Antigenic commonality and divergence of hemagglutinin-esterase-fusion protein among influenza D virus lineages revealed using epitope mapping.

Influenza D virus (IDV) is one of the causative agents of bovine respiratory disease complex, which is the most common and economically burdensome disease affecting the cattle industry, and the need for an IDV vaccine has been proposed to enhance disease control. IDVs are classified into five genetic lineages based on the coding sequences of the hemagglutinin-esterase-fusion (HEF) protein, an envelope glycoprotein, which is the main target of protective antibodies against IDV infection. Herein, we prepared a panel of monoclonal antibodies (mAbs) against the HEF protein of viruses of various lineages to investigate the antigenic characteristics of IDVs and found that the mAbs could be largely separated into three groups.

Differential role of NSs genes in the neurovirulence of two genogroups of Akabane virus causing postnatal encephalomyelitis.

Akabane virus (AKAV) is a member of the genus Orthobunyavirus, family Peribunyaviridae. In addition to AKAV strains that cause fetal Akabane disease, which is characterized by abortion in ruminants, some AKAV strains cause postnatal infection characterized by nonsuppurative encephalomyelitis in ruminants. Here, we focused on the NSs protein, a virulence factor for most viruses belonging to the genus Orthobunyavirus, and we hypothesized that this protein would act as a neurovirulence factor in AKAV strains causing postnatal encephalomyelitis.

Isolation and genetic characterization of a mammalian orthoreovirus from Vespertilio sinensis in Japan.

Throughout East Asia, Europe, and North America, mammalian orthoreovirus (MRV), for which bats have been proposed to be natural reservoirs, has been detected in a variety of domestic and wild mammals, as well as in humans. Here, we isolated a novel MRV strain (designated as Kj22-33) from a fecal sample from Vespertilio sinensis bats in Japan. Strain Kj22-33 has a 10-segmented genome with a total length of 23,580 base pairs.

Generation of a recombinant temperature-sensitive influenza D virus.

Influenza D virus (IDV) is a causative agent of the bovine respiratory disease complex (BRDC), which is the most common and costly disease affecting the cattle industry. For developing a candidate vaccine virus against IDV, we sought to produce a temperature-sensitive strain, similar to the live attenuated, cold-adapted vaccine strain available against the influenza A virus (IAV). To this end, we produced a recombinant IDV (designated rD/OK-AL) strain by introducing mutations responsible for the adaptation of the IAV vaccine strain to cold conditions and conferring sensitivity to high temperatures into PB2 and PB1 proteins using reverse genetics.

Direct evidence of fiber-protein-directed hemagglutination by canine adenoviruses.

Canine adenoviruses (CAdVs) are divided into two serotypes, CAdV1 and CAdV2, whose members mainly cause infectious hepatitis and laryngotracheitis, respectively, in canids. To gain insight into the molecular basis of viral hemagglutination, we constructed chimeric viruses whose fiber proteins or their knob domains, which play a role in viral attachment to cells, were swapped among CAdV1, CAdV2, and bat adenovirus via reverse genetics. The results revealed that, in each case, viral hemagglutination was specifically mediated by the fiber protein or knob domain, providing direct evidence for fiber-protein-directed receptor-binding characteristics of CAdVs.

Antiviral Susceptibilities of Distinct Lineages of Influenza C and D Viruses.

The emergence and spread of antiviral-resistant influenza viruses are of great concern. To minimize the public health risk, it is important to monitor antiviral susceptibilities of influenza viruses. Analyses of the antiviral susceptibilities of influenza A and B viruses have been conducted globally; however, those of influenza C and D viruses are limited.

Isolation of Bat Sarbecoviruses, Japan.

Surveillance of bat betacoronaviruses is crucial for understanding their spillover potential. We isolated bat sarbecoviruses from Rhinolophus cornutus bats in multiple locations in Japan. These viruses grew efficiently in cells expressing R.

Influenza A Virus Agnostic Receptor Tropism Revealed Using a Novel Biological System with Terminal Sialic Acid Knockout Cells.

Avian or human influenza A viruses bind preferentially to avian- or human-type sialic acid receptors, respectively, indicating that receptor tropism is an important factor for determining the viral host range. However, there are currently no reliable methods for analyzing receptor tropism biologically under physiological conditions. In this study, we established a novel system using MDCK cells with avian- or human-type sialic acid receptors and with both sialic acid receptors knocked out (KO).

Adaptation of the H7N2 Feline Influenza Virus to Human Respiratory Cell Culture.

During 2016-2017, the H7N2 feline influenza virus infected more than 500 cats in animal shelters in New York, USA. A veterinarian who had treated the cats became infected with this feline virus and showed mild respiratory symptoms. This suggests that the H7N2 feline influenza virus may evolve into a novel pandemic virus with a high pathogenicity and transmissibility as a result of mutations in humans.

Complete genome sequence of a novel bat mastadenovirus C strain isolated from Rhinolophus cornutus in Japan.

Here, we report a novel bat adenovirus strain isolated from apparently healthy bats of the species Rhinolophus cornutus in Japan. The genome of the isolate was 36,506 bp in length and encoded at least 33 proteins. Phylogenetic analysis of the DNA polymerase amino acid sequence, which provides one demarcation criterion for adenoviral species, indicated that the isolate belongs to the species Bat mastadenovirus C in the genus Mastadenovirus.

Influenza A Virus Infection in Domestic Ferrets.

Ferrets are animals that are known to be susceptible to influenza A virus (IAV) infection. To evaluate the risk of IAV transmission from diseased ferrets to humans, a survey was performed to detect specific antibodies against the H1, H3, H5, and H7 subtypes of IAV. Using enzyme-linked immunosorbent assay for hemagglutinin proteins, we found a high positive rate for the H1 (24.

Construction of an Influenza D Virus with an Eight-Segmented Genome.

Influenza D virus (IDV) may cause the bovine respiratory disease complex, which is the most common and costly disease affecting the cattle industry. Previously, we revealed that eight segments could be actively packaged in its single virion, suggesting that IDV with the seven-segmented genome shows an agnostic genome packaging mechanism. Herein, we engineered an eight-segmented recombinant IDV in which the or genes were separated from NS segment into independent segments (NS1 or NS2 segments, respectively), leading to monocistronic translation of each NS protein.

A potential bat adenovirus-based oncolytic virus targeting canine cancers.

Although a canine adenovirus (CAdV)-based oncolytic virus (OV) candidate targeting canine tumors has been reported, its oncolytic effect could be attenuated by CAdV vaccine-induced neutralizing antibodies in dog patients. To circumvent this issue, we focused on the bat adenovirus (BtAdV) strain, which was previously isolated from healthy microbats. We previously showed that this virus replicated efficiently in canine cell lines and did not serologically cross-react with CAdVs, suggesting that it may offer the possibility of an OV candidate for canine tumors.

Detection and Characterization of Bat Sarbecovirus Phylogenetically Related to SARS-CoV-2, Japan.

Epidemiology of bat Betacoronavirus, subgenus Sarbecovirus is largely unknown, especially outside China. We detected a sarbecovirus phylogenetically related to severe acute respiratory syndrome coronavirus 2 from Rhinolophus cornutus bats in Japan. The sarbecovirus' spike protein specifically recognizes angiotensin-converting enzyme 2 of R.

Establishment of a Simple and Efficient Reverse Genetics System for Canine Adenoviruses Using Bacterial Artificial Chromosomes.

Canine adenoviruses (CAdVs) are divided into pathotypes CAdV1 and CAdV2, which cause infectious hepatitis and laryngotracheitis in canid animals, respectively. They can be the backbones of viral vectors that could be applied in recombinant vaccines or for gene transfer in dogs and in serologically naïve humans. Although conventional plasmid-based reverse genetics systems can be used to construct CAdV vectors, their large genome size creates technical difficulties in gene cloning and manipulation.

Limited Cross-Protection Provided by Prior Infection Contributes to High Prevalence of Influenza D Viruses in Cattle.

Since its detection in swine, influenza D virus (IDV) has been shown to be present in multiple animal hosts, and bovines have been identified as its natural reservoir. However, it remains unclear how IDVs emerge, evolve, spread, and maintain in bovine populations. Through multiple years of virological and serological surveillance in a single order-buyer cattle facility in Mississippi, we showed consistently high seroprevalence of IDVs in cattle and recovered a total of 32 IDV isolates from both healthy and sick animals, including those with antibodies against IDV.

Establishment of a Reverse Genetics System for Influenza D Virus.

Influenza D virus (IDV) was initially isolated in the United States in 2011. IDV is distributed worldwide and is one of the causative agents of the bovine respiratory disease complex (BRDC), which causes high morbidity and mortality in feedlot cattle. The molecular mechanisms of IDV pathogenicity are still unknown.

Influenza D Virus of New Phylogenetic Lineage, Japan.

Influenza D virus (IDV) can potentially cause respiratory diseases in livestock. We isolated a new IDV strain from diseased cattle in Japan; this strain is phylogenetically and antigenically distinguished from the previously described IDVs.

Inactivation of human norovirus and its surrogate by the disinfectant consisting of calcium hydrogen carbonate mesoscopic crystals.

Human norovirus is one of the major causes of foodborne gastroenteritis, and it can be easily transmitted from infected person, virus-contaminated foods and environmental surfaces. Effective disinfection method is needed to stop the transmission of human norovirus. CAC-717 is a new disinfectant consisting of calcium hydrogen carbonate mesoscopic crystals.

Emerging lethal infectious bronchitis coronavirus variants with multiorgan tropism.

Infectious bronchitis virus (IBV) causes respiratory diseases in chickens and poses an economic threat to the poultry industry worldwide. Despite vaccine use, there have been field outbreaks of IBV in Taiwan. This study aimed to characterize the emerging IBV variants circulating in Taiwan.

Adaptation of H3N2 canine influenza virus to feline cell culture.

H3N2 canine influenza viruses are prevalent in Asian and North American countries. During circulation of the viruses in dogs, these viruses are occasionally transmitted to cats. If this canine virus causes an epidemic in cats too, sporadic infections may occur in humans because of the close contact between these companion animals and humans, possibly triggering an emergence of mutant viruses with a pandemic potential.