Investigating Influenza Virus Polymerase Activity in Feline Cells Based on the Influenza Virus Minigenome Replication System Driven by the Feline RNA Polymerase I Promoter.

Emerging influenza virus poses a health threat to humans and animals. Domestic cats have recently been identified as a potential source of zoonotic influenza virus. The influenza virus minigenome replication system based on the ribonucleic acid (RNA) polymerase I (PolI) promoter is the most widely used tool for investigating polymerase activity. It could help determine host factors or viral proteins influencing influenza virus polymerase activity in vitro. However, influenza virus polymerase activity has never been studied in feline cells thus far. In the present study, the feline RNA PolI promoter was identified in the intergenic spacer regions between adjacent upstream 28S and downstream 18S rRNA genes in the cat (Felis catus) genome using bioinformatics strategies. The transcription initiation site of the feline RNA PolI promoter was predicted. The feline RNA PolI promoter was cloned from CRFK cells, and a promoter size of 250 bp contained a sequence with sufficient PolI promoter activity by a dual-luciferase reporter assay. The influenza virus minigenome replication system based on the feline RNA PolI promoter was then established. Using this system, the feline RNA PolI promoter was determined to have significantly higher transcriptional activity than the human and chicken RNA PolI promoters in feline cells, and equine (H3N8) influenza virus presented higher polymerase activity than human (H1N1) and canine (H3N2) influenza viruses. In addition, feline myxovirus resistance protein 1 (Mx1) and baloxavir were observed to inhibit influenza virus polymerase activity in vitro in a dose-dependent manner. Our study will help further investigations on the molecular mechanism of host adaptation and cross-species transmission of influenza virus in cats.

Swine Interferon-Inducible Transmembrane Proteins Potently Inhibit African Swine Fever Virus Replication.

African swine fever virus (ASFV) causes an acute, hemorrhagic, and highly contagious disease in domestic swine, leading to significant economic losses to the global porcine industry. Restriction factors of innate immunity play a critical in host antiviral action. However, function of swine restriction factors of innate immunity on ASFV has been seldomly investigated. In this study, we determined five homologues of swine interferon-induced transmembrane proteins (SwIFITM [named SwIFITM1a, -1b, -2, -3, and -5]), and we found that they all exhibit potent antiviral activity against ASFV. Expression profile analysis indicated that these SwIFITMs are constitutively expressed in most porcine tissues. Whether infected with ASFV or treated with swine interferon, the expression levels of SwIFITMs were induced in vitro. The subcellular localization of SwIFITMs was similar to that of their human homologues. SwIFITM1a and -1b localized to the plasma membrane, SwIFITM2 and -3 focused on the cytoplasm and the perinuclear region, while SwIFITM5 accumulated in the cell surface and cytoplasm. The overexpression of SwIFITM1a, -1b, -2, -3, or -5 could significantly inhibit ASFV replication in Vero cells, whereas knockdown of these genes could enhance ASFV replication in PAMs. We blocked the constitutive expression of endogenous IFITMs in Vero cells using a CRISPR-Cas9 system and then infected them with ASFV. The results indicated that the knockout of endogenous IFITMs could enhance ASFV replication. Finally, we expressed five SwIFITMs in knockout Vero cell lines and then challenged them with ASFV. The results showed that all of the SwIFITMs had a strong antiviral effect on ASFV. This research will further expand the understanding of the anti-ASFV activity of porcine IFITMs.

Isolation and Genetic Characterization of Emerging H3N2 Canine Influenza Virus in Guangdong Province, Southern China, 2018-2021.

H3N2 canine influenza virus (CIV) emerged in dogs in China or Korea around 2005 and was first reported in 2008. In 2015, H3N2 CIV was detected in the United States and caused a huge outbreak. To date, H3N2 CIV is continuously circulating in dog populations in China, Korea, and the United States. For continuous monitoring of H3N2 CIV in China, we collected 180 dog nasal swab samples and 196 cat nasal swabs from veterinary hospitals in Guangdong Province between 2018 and 2021. Six emerging H3N2 CIV strains were isolated. Following full genome sequencing and phylogenetic analyses, we found that A/canine/Guangdong/1-3/2018 and A/canine/Guangdong/1-3/2021 diverged from the reported sequences of the Chinese H3N2 CIV strains. Moreover, we found that these H3N2 CIV strains belong to the group that contains US and northern China CIV strains in 2017 and 2019 and dominate in the dog population until 2021.

Novel parvovirus in cats, China.

Parvovirus is a common element of the feline virus group and usually causes gastroenteritis and leukopenia in cats. In this study, we identified a novel protoparvovirus from the Chinese domestic cats, which is genetically similar to canine bufavirus (98.0%-99.8%), but sharing low amino acid identities in the viral structural proteins 2 (VP2) (36.1-37.2%) to the well-known canine parvovirus type 2 and feline panleukopenia virus. This virus was provisionally designated as feline bufavirus (FBuV). Screening of fecal samples revealed a prevalence of 7.4% (19/257) in domestic cats. Diarrhea was present in 52.6% (10/19) of cats positive for FBuV. However, statistical analysis showed no association between FBuV and clinical signs. VP2 gene of the 19 field FBuV was sequenced and phylogenetic analysis demonstrated that FBuV determined from China had a genetic diversity. This study will strengthen the understanding of the epidemiology and genetic diversity of bufavirus and provide a foundation for further studies.

Genomic sequencing and characterization of a novel group of canine bufaviruses from Henan province, China.

Canine bufavirus (CBuV) is a novel protoparvovirus of dogs that was first reported in 2018 in Italy. The prevalence and genetic diversity of CBuV in China are not clear. In this study, a total of 115 canine fecal samples were collected from northern China in 2019, and two of the samples tested positive for CBuV DNA by PCR. These two field CBuV strains were designated Henan38 and Henan44. The complete genomic sequences of Henan38 and Henan44 were obtained by gap-filling PCR, sequenced, and assembled. Phylogenetic analysis demonstrated that the two strains clustered together in a novel group that was distant from previously reported CBuV strains. This study will strengthen our understanding of the epidemiology and genetic diversity of CBuV in China.

[Degradation of p-nitrophenol by high voltage pulsed discharge and ozone processes].

The vigorous oxidation by ozone and the high energy by pulsed discharge are utilized to degrade the big hazardous molecules. And these big hazardous molecules become small and less hazardous by this process in order to improve the biodegradability. When pH value is 8-9, the concentration of p-nitrophenol solution can be degraded by 96.8% and the degradation efficiency of TOC is 38.6% by ozone and pulsed discharge treatment for 30 mins. The comparison results show that the combination treatment efficiency is higher than the separate, so the combination of ozone and pulsed discharge has high synergism. It is approved that the phenyl degradation efficiency is high and the degradation efficiency of linear molecules is relative low.