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Abstract Classical swine fever is a highly contagious disease of swine caused by classical swine fever virus, an OIE list A pathogen. Epitope-based vaccines is one of the current focuses in the development of new vaccines against classical swine fever virus (CSFV). Two B-cell linear epitopes rE2-ba from the E2 glycoprotein of CSFV, rE2-a (CFRREKPFPHRMDCVTTTVENED, aa844-865) and rE2-b (CKEDYRYAISSTNEIGLLGAGGLT, aa693-716), were constructed and heterologously expressed in Escherichia coli as multiple epitope vaccine. Fifteen 6-week-old specified-pathogen-free (SPF) piglets were intramuscularly immunized with epitopes twice at 2-week intervals. All epitope-vaccinated pigs could mount an anamnestic response after booster vaccination with neutralizing antibody titers ranging from 1:16 to 1:256. At this time, the pigs were subjected to challenge infection with a dose of 1 × 106 TCID50 virulent CSFV strain. After challenge infection, all of the rE2-ba-immunized pigs were alive and without symptoms or signs of CSF. In contrast, the control pigs continuously exhibited signs of CSF and had to be euthanized because of severe clinical symptoms at 5 days post challenge infection. The data from in vivo experiments shown that the multiple epitope rE2-ba shown a greater protection (similar to that of HCLV vaccine) than that of mono-epitope peptide(rE2-a or rE2-b). Therefore, The results demonstrated that this multiple epitope peptide expressed in a prokaryotic system can be used as a potential DIVA (differentiating infected from vaccinated animals) vaccine. The E.coli-expressed E2 multiple B-cell linear epitopes retains correct immunogenicity and is able to induce a protective immune response against CSFV infection.

Glycyrrhetinic acid (GA) is an active component of licorice root that has long been used as a herbal medicine for the treatment of peptic ulcer, hepatitis, and pulmonary and skin diseases in Asia and Europe. In this study, we analyzed the effect of GA extracted from Glycyrrhiza uralensis Fisch. on the expression of Toll-like receptors (TLRs) that play key roles in regulating the innate immune response against invading pathogens. Stimulation of Ana-1 murine macrophages with GA induced a significant dose-dependent expression of TLR-4, and its mRNA expression that increased from 3-h post-treatment was approximately fivefold over the level in the mock-treated cells. No endotoxin contamination contributed to the GA-induced TLR-4 expression, because polymyxin B treatment did not alter the upregulated expression of TLR-4 in GA-treated cells. Several molecules, such as myeloid differentiation factor 88, interferon-β, and interleukin-6, which are involved in the TLR-4 downstream signaling pathway, were upregulated significantly in response to GA stimulation. Our findings demonstrate that GA is able to induce the expression of TLR-4 and activate its downstream signaling pathway. [ABSTRACT FROM PUBLISHER]