Genome analysis and development of infectious cDNA clone of a virulence-attenuated strain of foot-and-mouth disease virus type Asia 1 from China.

The RNA genome sequence of the rabbit passage-attenuated strain of foot-and-mouth disease virus (FMDV) Asia 1, ZB/CHA/58(att), was determined to be 8165 nt in length excluding the poly(C) tract in the 5' UTR and the poly(A) tail at the 3' end. ZB/CHA/58(att) was most similar to the vaccine strain Asia 1/YNBS/58 in genome sequence and there were no deletions or insertions within the deduced polyprotein between ZB/CHA/58(att) and YNBS/58, but there were a total of 25 substitutions at the amino acid level and an extra 19-nt stretch in the 5' UTR was found in ZB/CHA/58(att). An infectious full-length cDNA clone of ZB/CHA/58(att) was developed. Infectious virus could be recovered in BHK-21 cells transfected with the synthetic viral RNA transcribed in vitro. The plaque morphology, growth kinetics and antigenic profile of the infectious clone-derived virus (termed tZB) were indistinguishable from those induced by the parental virus. Furthermore, the virulence properties of ZB/CHA/58(att) and tZB were found to be highly similar in the mouse model. The availability of genome sequence information and infectious cDNA clone of the FMDV ZB/CHA/58(att) lays a new ground for further investigation of FMDV virulence determinants and development of new potent vaccine to FMD.

[Identification and comparison of neutralizing epitopes of glycoprotein E(rns) of classical swine fever virus].

Structural and envelope glycoprotein E(rns) (gp48) of classical swine fever virus (CSFV) is the second antigenic protein being responsible for eliciting neutralizing antibodies and conferring protective immunity. Infection of cells with CSFV is mediated by the interaction of glycoprotein E(rns) and E2 with the cell surface receptors. The glycoprotein E(rns) has been shown to contain RNase activity, which plays a role in the viral life cycle and is also involved in virus neutralization. Neutralizing epitopes of glycoprotein E(rns) had been mapped by screening a 12-mer random peptide phage display library using the neutralizing monoclonal antibodies (MAbs) 1B5, b4-22 and 24/16, raised against CSFV strain alfort T bingen and reacted with glycoprotein E(rns). Three major epitope (mimotope) motifs, WxNxxP, DKNR (Q) G and A (T) CxYxKN (around amino acid position aa351-aa356 or aa348-aa350, aa384-aa386 and aa322-aa323, aa380-aa386 of glycoprotein E(rns) of CSFV) were identified respectively and characterized immunologically by the MAbs, 1b5, b4-22 and 24/16. MAbs b4-22 and 24/16 shared a part of binding motif sequence KN, and recognized the similar antigenic domain on the glycoprotein E(rns) but showed a distinct pattern of flank sequence and reactivities with the mimotopes by Western blot and inhibition of immunofluorescent antibody analysis.

[Effect of staphylococcal enterotoxin B on ion electrophysiology and permeability in rabbit maxillary sinus epithelium].

OBJECTIVE: To study the barrier role of staphylococcal enterotoxin B (SEB) in rabbit maxillary sinus mucosa. METHODS: Rabbit maxillary sinus mucosal membrane was dissected under a surgical microscope. The short-circuit current (Isc), conductance (G) and its permeability to horseradish peroxidase (HRP) were evaluated by employing Ussing chamber technique. RESULTS: The stimulation of SEB enhanced Isc, G and its permeability to HRP of sinus epithelial barrier. The same results were obtained by applying tumor necrosis factor alpha (TNF-alpha) to rabbit maxillary sinus. Increase in TNF-alpha level in sinus mucosa was observed by the stimulation of SEB. Those pathophysiological abnormalities of sinus mucosa were abolished by pretreatment with anti-TNF-alpha antibody. CONCLUSION: The SEB has potential effects on rabbit maxillary sinus mucosal barrier, activates the immune cells in the mucosa, and plays certain roles in maxillary sinusitis.