Development of Vaccines Toward the Global Control and Eradication of Foot-and-mouth Disease

Luis L Rodriguez; Cyril G Gay

Disclosures

Expert Rev Vaccines. 2011;10(3):377-387. 

In This Article

Differentiating Infected from Vaccinated Animals

Exposure to structural FMDV capsid proteins as well as NSPs such a RNA polymerase through infection or vaccination will induce the production of antibodies to these proteins. The removal of NSPs from FMD vaccines enables the differential detection of antibodies to the NSPs in FMDV-infected animals. Thus, current DIVA strategies for FMD are based on the use of a diagnostic test that can differentiate the detection of antibodies to NSPs in infected versus vaccinated animals. For detailed information on DIVA tests and their role in control and eradication please see.[98–100]

Although the application of current DIVA strategies has been successfully implemented on a herd basis, there is still some concern of vaccinated animals becoming asymptomatic virus carriers without positive reaction to NSP serological tests.[101] Of particular concern is the fact that current vaccines may have residual NSPs (depending on the manufacturing process) that could result in the detection of NSP antibodies in vaccinated animals if multiple doses of vaccine are applied annually.[102–104] In addition, the application of the current DIVA strategy is dependent on diagnostic tests originally developed to determine FMDV infection and used primarily for surveillance and not necessarily as companion tests to vaccines.[100,105]

Since the ultimate goal of a DIVA strategy is to 'vaccinate to live,' it is paramount that vaccinated animals exposed to FMDV will not transmit virus. There is therefore a critical need for new and improved FMD vaccines and companion diagnostics specifically designed for DIVA and validated for the purpose intended. It is expected that the next generation of FMDV countermeasures will not only include vaccines designed with negative markers consisting of deletions of NSP epitopes, but also include companion antibody detection assays to determine exposure to FMDV, and direct antigen- or nucleic-acid detecting assays to verify that a vaccinated animal exposed to FMDV is not infected.

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