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Transmissible gastroenteritis virus (TGEV; Coronaviridae family) causes huge economic losses to the swine industry. MicroRNAs (miRNAs) play a regulatory role in viral infection and may be involved in the mammalian immune response. Here, we report a comprehensive analysis of host miRNA expression in TGEV-infected swine testis (ST) cells. Deep sequencing generated 3,704,353 and 2,763,665 reads from uninfected ST cells and infected ST cells, respectively. The reads were aligned to known Sus scrofa pre-miRNAs in miRBase 19, identifying 284 annotated miRNAs. Certain miRNAs were differentially regulated during TGEV infection. 59 unique miRNAs displayed significant differentially expression between the normal and TGEV-infected ST cell samples: 15 miRNAs were significantly up-regulated and 44 were significantly down-regulated. Stem-loop RT-PCR was carried out to determine the expression levels of specific miRNAs in the two samples, and the results were consistent with those of sequencing. Gene ontology enrichment analysis of host target genes demonstrated that the differentially expressed miRNAs are involved in regulatory networks, including cellular process, metabolic process, immune system process. This is the first report of the identification of ST cell miRNAs and the comprehensive analysis of the miRNA regulatory mechanism during TGEV infection, which revealed the miRNA molecular regulatory mechanisms for the viral infection, expression of viral genes and the expression of immune-related genes. The results presented here will aid research on the prevention and treatment of viral diseases.

Porcine cytomegalovirus (PCMV) is an immunosuppressive virus that mainly inhibits the immune function of the macrophage and T-cell lymphatic systems, and has caused huge economic losses to the porcine breeding industry. Molecular epidemiological investigation of PCMV is important for prevention and treatment, and this study is the first such investigation in Sichuan Province, Southwest China. A PCMV positive infection rate of 84.4% (865/1025) confirmed that PCMV is widely distributed in Sichuan Province. A phylogenetic tree was constructed based on the PCMV glycoprotein B gene (gB) nucleotide and amino acid sequences from 24 novel Sichuan isolates and 18 other PCMV gB sequences from Genbank. PCMV does not appear to have evolved into different serotypes, and two distinct sequence groups were identified (A and B). However, whether PCMV from this region has evolved into different genotypes requires further research. Analysis of the amino acid sequences confirmed the conservation of gB, but amino acid substitutions in the major epitope region have caused antigenic drift, which may have altered the immunogenicity of PCMV.