Temporal insight into the natural generation of a new reassortant porcine influenza virus in a swine holding

Review of genome sequencing technologies in molecular characterization of influenza A viruses in swine

The rapidly evolving antigenic diversity of influenza A virus (IAV) genomes in swine makes it imperative to detect emerging novel strains and track their circulation. We analyzed in our review the sequencing technologies used for subtyping and characterizing swine IAV genomes. Google Scholar, PubMed, and International Nucleotide Sequence Database Collaboration (INSDC) database searches identified 216 studies that have utilized Sanger, second-, and third-generation sequencing techniques to subtype and characterize swine IAV genomes up to 31 March 2021. Sanger dideoxy sequencing was by far the most widely used sequencing technique for generating either full-length (43.0%) or partial (31.0%) IAV genomes in swine globally; however, in the last decade, other sequencing platforms such as Illumina have emerged as serious competitors for the generation of whole-genome sequences of swine IAVs. Although partial HA and NA gene sequences were sufficient to determine swine IAV subtypes, whole-genome sequences were critical for determining reassortments and identifying unusual or less frequently occurring IAV subtypes. The combination of Sanger and second-generation sequencing technologies also greatly improved swine IAV characterization. In addition, the rapidly evolving third-generation sequencing platform, MinION, appears promising for on-site, real-time sequencing of complete swine IAV genomes. With a higher raw read accuracy, the use of the MinION could enhance the scalability of swine IAV testing in the field and strengthen the swine IAV disease outbreak response.

Carvacrol inhibits the excessive immune response induced by influenza virus A via suppressing viral replication and TLR/RLR pattern recognition

ETHNOPHARMACOLOGICAL RELEVANCE

Carvacrol, a monoterpene phenol from Mosla chinensis Maxim, which is a commonly Chinese herbal medicine. The most important pharmacology of it is dispelling exogenous evils by increasing perspiration. And it is the gentleman medicine in the Chinese herbal compound prescription of Xin-Jia-Xiang-Ru-Yin, mainly for the treatment of summer colds with dampness including influenza virus A infection.

AIM OF THE STUDY

Our preliminary study verified that the Xin-Jia-Xiang-Ru-Yin could inhibit acute lung injury of mice with influenza virus A infection. And there have been some reports implicating the high antimicrobial activity of carvacrol for a wide range of product preservation, but little research including the effects of it on viral infection. The aim of this study was to reveal the antiviral effects of carvacrol, the main constituent in Mosla chinensis Maxim.

MATERIALS AND METHODS

Initially, C57BL/6 mice were grouped and intranasally administered FM1 virus to construct viral infection models. After treatment with ribavirin and carvacrol for 5 days, all mice were euthanized, and specimens were immediately obtained. Histology, flow cytometry and Meso Scale Discovery (MSD) analysis were used to analyze pathological changes in lung tissue, the expression levels of cytokines and the differentiation and proportion of CD4+ T cells subsets, while Western blot and qRT-PCR were used to detect the expression of related proteins and mRNA.

RESULTS

Carvacrol attenuated lung tissue damage, the proportions of Th1, Th2, Th17 and Treg in CD4+ T cells and the relative proportions of Th1/Th2 and Th17/Treg cells. Carvacrol inhibited the expression of inflammation-associated cytokines including IFN-γ, IL-2, IL-4, IL-5, IL-12 and TNF-ɑ, IL-1, IL-10, IL-6. Decreased levels of TLR7, MyD88, IRAK4, TRAK6, NF-κB, RIG-I, IPS-I and IRF mRNA in carvacrol-treated mice were observed comparing to the mice in VC group. Further, the total expression of RIG-I, MyD88 and NF-κB proteins had increased significantly in the VC group but reduced obviously in the group treated with ribavirin or carvacrol.

CONCLUSIONS

These results indicate that carvacrol is a potential alternative treatment for the excessive immune response induced by influenza virus A infection, the cold-fighting effect of Mosla chinensis Maxim may depend on the anti-virus of carvacrol.