Genetic characterization of H1N2 influenza a virus isolated from sick pigs in Southern China in 2010.

In China H3N2 and H1N1 swine influenza viruses have been circulating for many years. In January 2010, before swine were infected with foot and mouth disease in Guangdong, some pigs have shown flu-like symptoms: cough, sneeze, runny nose and fever. We collected the nasopharyngeal swab of all sick pigs as much as possible. One subtype H1N2 influenza viruses were isolated from the pig population. The complete genome of one isolate, designated A/swine/Guangdong/1/2010(H1N2), was sequenced and compared with sequences available in GenBank. The nucleotide sequences of all eight viral RNA segments were determined, and then phylogenetic analysis was performed using the neighbor-joining method. HA, NP, M and NS were shown to be closely to swine origin. PB2 and PA were close to avian origin, but NA and PB1were close to human origin. It is a result of a multiple reassortment event. In conclusion, our finding provides further evidence about the interspecies transmission of avian influenza viruses to pigs and emphasizes the importance of reinforcing swine influenza virus (SIV) surveillance, especially before the emergence of highly pathogenic FMDs in pigs in Guangdong.

Insights into the evolutionary history and epidemiological characteristics of the emerging lineage 1 porcine reproductive and respiratory syndrome viruses in China.

The newly emerged lineage 1 porcine reproductive and respiratory syndrome viruses (PRRSVs) (especially the NADC30-like and NADC34-like viruses) have posed a direct threat to the Chinese pig industry since 2013. The phylogenetic, epidemic, and recombinant properties of these viruses have not yet systematically analysed in China. This report presents regular surveillance and field epidemiological studies for PRRSV across China from 2007 to 2019. From over 4,000 detected clinical samples, 70 open reading frame five sequences and four complete genomes of lineage 1 viruses were successfully obtained. Combined with global data, we conducted an extensive and systematic molecular phylogeny analysis using a maximum likelihood tree. The Chinese lineage 1 viruses were clustered, and their temporal and spatial distribution was further explored. Multiple viral introductions of lineage 1 virus from the United States to China were detected, and some became endemic in China. There are three sub-lineage 1 clusters: lineage 1.5 (NADC34-like), lineage 1.6 and New Intro cluster (NADC30-like). These viruses show high genetic diversity and a wide distribution in China, with Henan Province showing the highest diversity. Moreover, Chinese lineage 1 viruses have developed an endemic NADC30-like cluster. The demographic feature of this cluster showed a more or less constant population expansion history with a recent decreasing trend. Moreover, the genome recombination of Chinese lineage 1 with two dominant clusters (Chinese HP-PRRSVs: lineage 8.7 and VR2332-like: lineage 5.1) was frequently detected, both of which have commercial vaccine strains available. Furthermore, recombination hotspots were discovered near NSP9 and ORF2-4 regions of the genome. Overall, these findings provide important insights into the evolution and geographical diversity of Chinese lineage 1 PRRSV. These results will facilitate the development of programmes for the control and prevention of the emerging lineage 1 viruses in China.

Isolation and Phylogenetic Analysis of H1N1 Swine Influenza Virus from Sick Pigs in Southern China.

Two swine influenza (SI) H1N1 virus was isolated from a pig during a severe outbreak of respiratory disease in south China. The two H1N1 influenza viruses were classical SI virus. A/swine/Guangdong/L6/09 is classical SI virus of recent years, which is of the main SI virus in China. Howere, A/swine/Guangdong/L3/09 was closet to A/swine/Iowa/1931, which was the first isolated SI virus and had demonstrated significant pathogenicity in animal models. The results of phylogenetic analysis of A/swine/Guangdong/L3/09 showed a close relationship with the 1918 pandemic virus. The results suggested that the previous SI virus appeared again. Whether, it brought a new pandemic to pigs deserves more attention.

Antimicrobial resistance in Escherichia coli isolates from food animals, animal food products and companion animals in China.

One thousand and thirty Escherichia coli isolates from food animals, animals-derived foods, and companion animals between 2007 and 2008 in Southern China were used to investigate their antimicrobial susceptibility to 14 different antimicrobials by the standard agar dilution method. More than 70% of isolates showed resistance to tetracycline, trimethoprim-sulphamethoxazole, nalidixic acid, and ampicillin. In general, resistance was less frequent in companion animal isolates vs food animals isolates, but cephalosporin and amikacin resistance was more frequent in companion animal isolates, 42.6% to 56.2% vs 14.1% to 24.3%, and 28.5% vs 18.8%, respectively, which was most likely due to the common use of these antimicrobials as treatment in pet animals. Fluoroquinolones resistance was high in all animal isolates (>50%). Food products showed lowest resistance among isolates from these three resources. PFGE analysis indicated that a majority of multidrug-resistant E. coli isolates showed unique, unrelated PFGE profiles and were unlikely to be the spread of a specific clone. This study provides useful information about the prevalence of antimicrobial resistance in E. coli isolated from animals and food products in China and provided evidence of the linkage of the use of antimicrobials in animals and its selection of antimicrobial resistance in bacterial isolates. The data from this study further warns the prudent use of antimicrobials in food and pet animals to reduce the risks of transmission of antimicrobial resistance zoonotic pathogen to humans.