Open session of the standing technical committee of the EUFMD- 2000

5 analysis of the complete capsid-coding region showed that the virus could be divided into two groups which were distinct from the O1 Manisa and O1 Kaufbeuren reference strains. Representatives of both groups were found in Vietnam. Antigenic analysis (LPB-ELISA and Mab profiling) was also able to distinguish the two virus groups.

Dr. A.R. Samuel also gave a presentation (Appendix 7) on the genetically diverse isolates of FMDV which exhibit remarkable amino acid conservation at their neutralizing antigenic sites. Eighteen genetically diverse FMD type O viruses were examined using a panel of neutralizing MAbs. Comparison of the deduced aminoacid sequences in the previously defined five antigenic sites revealed aminoacid substitutions which were conservative in nature. These changes were usually limited to one or two different aminoacids.

Prof. Alexandersen presented a paper (Appendix 8) on the early pathogenesis of FMD in pigs: a quantitative time course study using a newly developed Taq Man RT PCR assay. Selected tissues were collected from pigs infected by contact with FMDV serotype O1 Lausanne and analyzed using a) real time PCR and b) virus titration in cell culture as well as histopathology. It was proposed that after contact exposure virus deposits in the pharynx, spreads to the regional lymph nodes and then produces an initial viraemia. Following this the majority of virus amplification is generated by several replication cycles in epithelial cells and further viraemic spread.

Dr. M. Amadori presented a paper (Appendix 9) on the IgA response of cattle to FMDV infection in probang and saliva samples. Probang and saliva samples from experimentally challenged cattle using FMDV serotype O1 Manisa were collected up to 234 days pi and subjected to IgA antibody ELISA. Virus isolation and RT PCR was carried out on the probang samples. Mucosal IgA antibody detection seems to be more reliable than virus detection in probang samples since a) virus presence in probang samples was found to be intermittent and b ) IgA response in saliva of “carrier” animals was much more constant and was still detectable even when no virus could be detected.

Conclusions: 1. The pandemic strain of FMDV serotype O is a major threat to Europe since it has shown to be able to spread very extensively and quickly.

2. Phylogenetic analysis has been shown to be very valuable for the characterization of the recent outbreaks and the identification of their origin.

3. Disease awareness can be sub-optimal in a country which has not experienced FMD for a long period of time.

4. Variable pathogenicity of the Japanese 2000 type O FMD isolate has been shown although the experiment was done with few animals.

5. Relatively high doses of FMDV are required to infect pigs by the aerosol route.