Inhibition of Ultraviolet B-Induced Expression of the Proinflammatory Cytokines TNF-α and VEGF in the Cornea by Fucoxanthin Treatment in a Rat Model.

Ultraviolet B (UVB) irradiation is the most common cause of radiation damage to the eyeball and is a risk factor for human corneal damage. We determined the protective effect of fucoxanthin, which is a carotenoid found in common edible seaweed, on ocular tissues against oxidative UVB-induced corneal injury. The experimental rats were intravenously injected with fucoxanthin at doses of 0.5, 5 mg/kg body weight/day or with a vehicle before UVB irradiation. Lissamine green for corneal surface staining showed that UVB irradiation caused serious damage on the corneal surface, including severe epithelial exfoliation and deteriorated epithelial smoothness. Histopathological lesion examination revealed that levels of proinflammatory cytokines, including tumor necrosis factor-α (TNF-α) and vascular endothelial growth factor (VEGF), significantly increased. However, pretreatment with fucoxanthin inhibited UVB radiation-induced corneal disorders including evident preservation of corneal surface smoothness, downregulation of proinflammatory cytokine expression, and decrease of infiltrated polymorphonuclear leukocytes from UVB-induced damage. Moreover, significant preservation of the epithelial integrity and inhibition of stromal swelling were also observed after UVB irradiation in fucoxanthin-treated groups. Pretreatment with fucoxanthin may protect against UVB radiation-induced corneal disorders by inhibiting expression of proinflammatory factors, TNF-α, and VEGF and by blocking polymorphonuclear leukocyte infiltration.

Characterization of two novel porcine reproductive and respiratory syndrome virus isolates with deletions in the GP2 gene.

Two newly emerged, porcine reproductive and respiratory syndrome virus (PRRSV) strains (Henan-A10 and A11) were isolated from the sera of aborting sows. Interestingly, both of the isolates could replicate in primary porcine alveolar macrophage (PAM) cells but not in MARC-145 cells. A phylogenetic tree based on the complete genome was constructed and the results showed that Henan-A10 and A11 were most closely related to other highly pathogenic PRRSV (HP-PRRSV) strains. However, genomic sequence analysis showed that Henan-A10 and A11 shared only 96.8-97.8% nucleotide identity with the representative HP-PRRSV strain JXA1. Notably, a 10 amino acids deletion in the GP2 endodomain was identified for the first time. A full-length, infectious cDNA clone of HuN4-F112 (attenuated strain from a HP-PRRSV) was used to construct a chimeric clone with the corresponding deletion in GP2. We found that the deletion did not affect viral growth in MARC-145 cells, indicating that the endodomain of PRRSV GP2 may be variable.

Identification of two dominant linear epitopes on the GP3 protein of highly pathogenic porcine reproductive and respiratory syndrome virus (HP-PRRSV).

Glycosylated protein 3 (GP3) of PRRSV is variable between different PRRSV strains, so it is helpful for subtype classifying by using distinct epitopes. In this study, two dominant linear GP3 epitopes that were recognized by highly dilute serum in an enzyme-linked immunosorbent assay (ELISA) were identified. Sequence alignments of 36 North American (NA) PRRSV isolates revealed that the epitope H(87)DELGFMV(94) is well conserved, whereas the epitope T(59)RQAAAEILE(68) differs in other low-virulence NA-type strains, which have at least one amino acid mutation in this region. A mutational analysis revealed that none of these mutations could be recognized by the purified antibodies directed against the corresponding epitope, indicating that the genetic variations altered the antigenicity of the antigenic region. Using ELISA, we also found that antibodies directed against the two epitopes were present in more than 45 of 50 HP-PRRS-positive pig sera, suggesting that their antigenicity is excellent in vivo.

Pseudorabies virus variant in Bartha-K61-vaccinated pigs, China, 2012.

The widely used pseudorabies virus (PRV) Bartha-K61 vaccine has played a key role in the eradication of PRV. Since late 2011, however, a disease characterized by neurologic symptoms and a high number of deaths among newborn piglets has occurred among Bartha-K61-vaccinated pigs on many farms in China. Clinical samples from pigs on 15 farms in 6 provinces were examined. The PRV gE gene was detectable by PCR in all samples, and sequence analysis of the gE gene showed that all isolates belonged to a relatively independent cluster and contained 2 amino acid insertions. A PRV (named HeN1) was isolated and caused transitional fever in pigs. In protection assays, Bartha-K61 vaccine provided 100% protection against lethal challenge with SC (a classical PRV) but only 50% protection against 4 challenges with strain HeN1. The findings suggest that Bartha-K61 vaccine does not provide effective protection against PRV HeN1 infection.

Highly pathogenic porcine reproductive and respiratory syndrome virus GP5 B antigenic region is not a neutralizing antigenic region.

In 2006, highly pathogenic porcine reproductive and respiratory syndrome virus (HP-PRRSV) caused great economic losses emerged in China and continues to be a threat for the pig industry. B antigenic region (AR) ((37)SHL/FQLIYNL(45)) of GP5 was considered to be a major linear neutralizing AR in PRRSV classical strains. However, peptide-purified antibodies against this AR did not neutralize PRRSV in a recent report. Compared with classical PRRSV, one amino acid mutation (L/F(39)→ I(39)) was found in B AR of HP-PRRSV. To study the ability of B AR of HP-PRRSV to induce neutralizing antibody (NA) in vitro and in vivo, rabbit antisera against B AR with and without the mutation and pig hyperimmune sera with high titer of NAs against HP-PRRSV were prepared. Immunofluorescence assays (IFA) showed that the two rabbit antisera both had reactivity to classical PRRSV CH-1a and HP-PRRSV HuN4 with no observable difference in IFA titer. However, antisera did not have neutralizing activity against classical PRRSV CH-1a and HP-PRRSV HuN4. No correlation was observed between the levels of anti-B AR peptide antibodies and NAs in pig hyperimmune sera that were detected by indirect ELISA and virus neutralization, respectively. B AR peptide-specific serum antibodies had no neutralizing activity and, GST-B fusion protein could not inhibit neutralization of NAs in pig hyperimmune sera. Based on these findings, we conclude that B AR of HP-PRRSV is not a neutralizing AR of HP-PRRSV GP5.

Isolation of serotype 2 porcine teschovirus in China: evidence of natural recombination.

Porcine teschovirus (PTV), the pathogen of porcine polioencephalomyelitis, is a member of the family Picornaviridae. In this study, a new PTV strain (designated as JF613) was isolated from pigs in China. It was confirmed by the specific CPE on susceptible cells, RT-PCR and nucleotide sequencing. Analysis of its amino acids sequence of complete polyprotein indicated that the isolate belongs to serotype 2. Genetic recombination is a well-known phenomenon for picornavirus which has been demonstrated in many other members of the family, but it remains so far unclear whether recombination occurs in PTV. To detect possible recombination events, 30 sequences of complete coding regions of PTV strains accessible in GenBank were examined. Putative recombinant sequence was identified with the use of SimPlot program. The result showed that the genomic sequence of our isolate exhibited highest similarities with strains of serotypes 2 and 5, respectively, in two crossover regions, suggesting the recombination event in PTV. Then the mosaic structure of viral genome was confirmed by bootscanning and genetic algorithm for recombination detection (GARD). This represents the first PTV-2 isolate in China. Furthermore, our study provided the first evidence of natural recombination in PTV and indicated that homologous recombination may be a driving force in PTV evolution.

Cloning and identification of porcine programmed death 1.

Programmed death 1 (PD-1) is a member of the immunoglobulin (Ig) superfamily, which is expressed on activated T cells, B cells and monocytes. Many researches have demonstrated that a high level of PD-1 expression is closely related to persistent infection and immune evasion in some human infections. In order to study the relationship between PD-1 expression and persistent infections caused by some porcine viruses, we first cloned the porcine PD-1 from porcine PBMCs based on the blast result in the EST database using the human PD-1 sequence. Sequence analysis showed that the cloned PD-1 molecule shares 63 and 54% amino acid sequence identity with human and murine PD-1, respectively. Its molecular structure is also similar to that of human and murine PD-1, containing an IgV-like domain in the extracellular region and two immune regulatory motifs in its cytoplasmic tail. The in vitro T cell proliferation assay showed that the cloned PD-1 could inhibit porcine T cell proliferation by 71% and secretion of IFN-gamma and IL-2 by 64 and 53%, respectively. These data suggest that porcine PD-1 negatively regulates the porcine immune response in a similar manner to that of its counterpart in the human and mouse immune system.