Genetic analysis and pathogenicity of different sequence types of Streptococcus suis isolated from pigs in southern China.

In this study, 52 Streptococcus suis isolates from pigs in southern China were divided into four known sequence types (STs) and six new STs, using multilocus sequence typing. Ten representative isolates were selected from 10 STs for the analysis of whole genome sequences. Virulence was assessed in 10 isolates, which were classified into three pathogenic groups. The prevalence of virulence-associated factors in the moderately pathogenic group was higher than that in the highly pathogenic group. The isolates from ST1 complex and serotype 2 were allocated to the moderately pathogenic group, while the isolates from the highly pathogenic group belonged to the non-ST1 complex and non-serotype 2. Three clusters were obtained based on multilocus sequence typing sequences: cluster III isolates from the nasal cavity of healthy pigs were classified into the highly pathogenic group and showed many peculiarities compared with cluster I and II isolates in virulence genotypes, genetic typing and pathogenesis, indicating a potential independent evolutionary line. Our results suggest that S. suis infections in China are becoming more complicated with constantly mutating isolates, which makes it difficult to distinguish their virulence by recognized typing methods. Thus, increased investigation and monitoring of these infections should be a priority for the swine industry in China.

Complete genomic characteristics and pathogenic analysis of the newly emerged classical swine fever virus in China.

BACKGROUND: Classical swine fever (CSF) is one of the most devastating and highly contagious viral diseases in the world. Since late 2014, outbreaks of a new sub-genotype 2.1d CSF virus (CSFV) had caused substantial economic losses in numbers of C-strain vaccinated swine farms in China. The objective of the present study was to explore the genomic characteristics and pathogenicity of the newly emerged CSFV isolates in China during 2014-2015. RESULTS: All the new 8 CSFV isolates belonged to genetic sub-genotype 2.1d. Some genomic variations or deletions were found in the UTRs and E2 of these new isolates. In addition, the pathogenicity of HLJ1 was less than Shimen, suggesting the HLJ1 of sub-genotype 2.1d may be a moderated pathogenic isolate and the C-strain vaccine can supply complete protection. CONCLUSIONS: The new CSFV isolates with unique genomic characteristics and moderate pathogenicity can be epidemic in many large-scale C-strain vaccinated swine farms. This study provides the information should be merited special attention on establishing prevention and control policies for CSF.

Identification of host cellular proteins that interact with the M protein of a highly pathogenic porcine reproductive and respiratory syndrome virus vaccine strain.

BACKGROUND: The highly pathogenic porcine reproductive and respiratory syndrome virus (HP-PRRSV) continues to pose one of the greatest threats to the swine industry. M protein is the most conserved and important structural protein of PRRSV. However, information about the host cellular proteins that interact with M protein remains limited. METHODS: Host cellular proteins that interact with the M protein of HP-PRRSV were immunoprecipitated from MARC-145 cells infected with PRRSV HuN4-F112 using the M monoclonal antibody (mAb). The differentially expressed proteins were identified by LC-MS/MS. The screened proteins were used for bioinformatics analysis including Gene Ontology, the interaction network, and the enriched KEGG pathways. Some interested cellular proteins were validated to interact with M protein by CO-IP. RESULTS: The PRRSV HuN4-F112 infection group had 10 bands compared with the control group. The bands included 219 non-redundant cellular proteins that interact with M protein, which were identified by LC-MS/MS with high confidence. The gene ontology and Kyoto encyclopedia of genes and genomes (KEGG) pathway bioinformatic analyses indicated that the identified proteins could be assigned to several different subcellular locations and functional classes. Functional analysis of the interactome profile highlighted cellular pathways associated with protein translation, infectious disease, and signal transduction. Two interested cellular proteins-nuclear factor of activated T cells 45 kDa (NF45) and proliferating cell nuclear antigen (PCNA)-that could interact with M protein were validated by Co-IP and confocal analyses. CONCLUSIONS: The interactome data between PRRSV M protein and cellular proteins were identified and contribute to the understanding of the roles of M protein in the replication and pathogenesis of PRRSV. The interactome of M protein will aid studies of virus/host interactions and provide means to decrease the threat of PRRSV to the swine industry in the future.

Complete Genome Sequence of Classical Swine Fever Virus Strain JSZL, Belonging to a New Subgenotype, 2.1d, Isolated in China in 2014.

The complete genome sequence of classic swine fever virus (CSFV) strain JSZL was determined in this study. JSZL was originally isolated from an immune pig farm in Jiangsu Province, China. JSZL is more closely related to subgenotype 2.1b than to 2.1a and 2.1c. Importantly, JSZL was classified into a new subgenotype, 2.1d.