Reconstructing the evolutionary history of pandemic foot-and-mouth disease viruses: the impact of recombination within the emerging O/ME-SA/Ind-2001 lineage.

Foot-and-mouth disease (FMD) is a highly contagious disease of livestock affecting animal production and trade throughout Asia and Africa. Understanding FMD virus (FMDV) global movements and evolution can help to reconstruct the disease spread between endemic regions and predict the risks of incursion into FMD-free countries. Global expansion of a single FMDV lineage is rare but can result in severe economic consequences. Using extensive sequence data we have reconstructed the global space-time transmission history of the O/ME-SA/Ind-2001 lineage (which normally circulates in the Indian sub-continent) providing evidence of at least 15 independent escapes during 2013-2017 that have led to outbreaks in North Africa, the Middle East, Southeast Asia, the Far East and the FMD-free islands of Mauritius. We demonstrated that sequence heterogeneity of this emerging FMDV lineage is accommodated within two co-evolving divergent sublineages and that recombination by exchange of capsid-coding sequences can impact upon the reconstructed evolutionary histories. Thus, we recommend that only sequences encoding the outer capsid proteins should be used for broad-scale phylogeographical reconstruction. These data emphasise the importance of the Indian subcontinent as a source of FMDV that can spread across large distances and illustrates the impact of FMDV genome recombination on FMDV molecular epidemiology.

Development of an inactivated 3C(pro)-3ABC (mu3ABC) ELISA to differentiate cattle infected with foot and mouth disease virus from vaccinated cattle.

Foot and mouth disease, a highly contagious disease of cloven-hoofed animals, is still endemic in Asia, Africa, and a few countries in South America. Subclinical and persistent infections usually occur in vaccinated cattle exposed to FMDV. Successful control and eradication measures need a diagnostic assay that can distinguish between immune responses to infection and vaccination. The non-structural 3ABC ELISA is the most reliable differential diagnostic assay. However, expression of the native 3ABC gene in insect cells yielded truncated versions of the proteins; thus, a monoclonal antibody to capture digested proteins is needed to develop the assay. The purpose of this study was to develop a simple indirect 3ABC ELISA using complete 3ABC protein. The full-length mutated 3ABC protein with inactive 3C(pro) (mu3ABC) gene was constructed. The histidine-tagged mu3ABC protein was produced in insect cells for easy purification and measuring. This permits simple assay design and reproducible assay development. mu3ABC ELISA had diagnostic specificity and sensitivity of 96.6% and 84%, respectively, compared to Ceditest(®) FMDV-NS. Agreement of both assays was excellent with κ value of 0.823 (p<0.05). The mu3ABC ELISA could distinguish infected from vaccinated animals. These factors are necessary for the successful development of an in-house NSP-based ELISA. Availability of a reliable assay with acceptable costs would facilitate successful disease control and the establishment of disease-free zones. Expansion of such zones may ultimately decrease the risk of introducing FMDV into disease-free countries, thus accelerating global FMD control.

Multiple origins of foot-and-mouth disease virus serotype Asia 1 outbreaks, 2003-2007.

We investigated the molecular epidemiology of foot-and-mouth disease virus (FMDV) serotype Asia 1, which caused outbreaks of disease in Asia during 2003-2007. Since 2004, the region affected by outbreaks of this serotype has increased from disease-endemic countries in southern Asia (Afghanistan, India, Iran, Nepal, Pakistan) northward to encompass Kyrgyzstan, Tajikistan, Uzbekistan, several regions of the People's Republic of China, Mongolia, Eastern Russia, and North Korea. Phylogenetic analysis of complete virus capsid protein 1 (VP1) gene sequences demonstrated that the FMDV isolates responsible for these outbreaks belonged to 6 groups within the Asia 1 serotype. Some contemporary strains were genetically closely related to isolates collected historically from the region as far back as 25 years ago. Our analyses also indicated that some viruses have spread large distances between countries in Asia within a short time.

Development and evaluation of an indirect enzyme-linked immunosorbent assay for detection of foot-and-mouth disease virus nonstructural protein antibody using a chemically synthesized 2B peptide as antigen.

Forty peptides were synthesized corresponding to hydrophilic clusters of amino acids within the sequences of foot-and-mouth disease virus (FMDV) nonstructural proteins (NSP). Six peptides were studied in more detail and the most promising, a 2B peptide, was evaluated in enzyme-linked immunosorbent assay (ELISA) using sera from naive, vaccinated, and vaccinated-and-challenged cattle as well as bovine sera from field outbreaks. The performance of the new NSP peptide ELISA was compared to that of 4 commercial NSP ELISA kits. Antibody to 2B was detectable from the end of the first week to the second week after infection in most of the nonvaccinated animals and by the second to third week in vaccinated-and-challenged animals. The sensitivity of the 2B peptide ELISA was comparable to the 3ABC Ceditest (Ceditest FMDV-NS, Cedi Diagnostics B.V.; Chung et al., 2002). With some modification and further validation, this 2B test could be useful as a screening or conformational NSP test in postvaccination surveillance for FMD.