Thursday, 10 August 2017 15:01

Mix-and-match vaccine hopes to curtail outbreaks in livestock

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Published in mBiosphere

Scientists have designed a vaccine that protects animals against 7 foot-and-mouth disease virus (FMDV) serotypes. The research, published in the Journal of Virology, promises to halt the types of outbreaks that can lead to animal quarantine and trade interruptions in affected countries. 

JVirology: Rapid engineering of foot-and-mouth disease vaccine and challenge viruses

In their work, first author Seo-Yong Lee and senior scientist Jong-Hyeon Park used a vaccine FMDV strain to make 7 constructs, each with a capsid-encoding gene (P1) from a different serotype. Individual chimeric viruses were first inactivated and tested for neutralizing antibody production in goats. Chimeric viruses from these constructs were then generated in cell culture, and three viral serotypes (O, A, and Asia1) were combined into a vaccine that was administered into pigs.

FMDV figureUnvaccinated pigs (134 + 135) and vaccinated pigs (136-139) were assessed for clinical score, viral excretion from the oral cavity, and viremia. Source.

Pigs injected with the trivalent viral cocktail were able to repress viral replication, with low levels of viral RNA detectable only intermittently in the 10-day experiment, whereas unvaccinated animals had levels of viral RNA as high as 103 copies/0.1 ml (see figure, right). Vaccination also protected the animals from symptoms of disease, while unvaccinated animals displayed signs of FMD 2 days after infection.

Ideally, scientists would develop a single vaccine effective against all serotypes with long-lasting memory; current vaccines confer protection for only 4-6 months. However, this chimeric vaccine strain vaccination strategy would allow scientists to control outbreaks by creating a specific protection in animals against the outbreak strain/strains. The use of different P1 genes expressed in the well-characterized O Manisa strain retains several desired characteristics, including the ability to replicate in many cell lines. The researchers also propose incorporating marker genes into the viral backbone, to help differentiate infected from vaccinated animals during a disease outbreak.

A recent FMDV outbreak in Colombia resulted in a suspension of Colombian beef shipments, and more than 3,000 animals were put down in attempts to control spread of the disease. FMDV has been eradicated from the United States, but the threat of the disease is taken so seriously that a the livestock industry have asked Congress to include  $750 million for enhancing the available FMD vaccine bank in the 2018 Farm Bill, with an extra $100 million for research and public health grants. The research here demonstrates a new vaccine platform that may be able to help responders rapidly provide protective vaccines during disease outbreaks.

FMDV photo source

Last modified on Thursday, 10 August 2017 15:18
Julie Wolf

Julie Wolf is the ASM Science Communications Specialist. She contributes to the ASM social media and blog network and hosts the Meet the Microbiologist podcast. She also runs workshops at ASM conferences to help scientists improve their own communication skills. Follow Julie on Twitter for more ASM and microbiology highlights at @JulieMarieWolf.

Julie earned her Ph.D. from the University of Minnesota, focusing on medical mycology and infectious disease. Outside of her work at ASM, she maintains a strong commitment to scientific education and teaches molecular biology at the community biolab, Genspace. She lives in beautiful New York City.