IRTA-CReSA researchers José Ignacio Núñez and Álvaro López visited the INIA-CISA facilities within the framework of a collaborative project to transfer methodologies for massive virus sequencing.
Rift Valley fever is an endemic disease of the African continent that mainly affects sheep, cattle and camelids, but totally unknown in Europe. The virus that causes this disease is transmitted through the bite of infected mosquitoes, between animals and also from animals to people, so it is also considered a zoonotic disease.
One of the lines of the INIA-CISA team led by Belén Borrego and Alejandro Brun, is to explore different strategies against this virus. One of the possible strategies is to use attenuated viruses as vaccine candidates. So far, the first experiments with mice have been performed. First, treating the RVFV virus with the drug favipiravir, which introduces random mutations into the viral genome reducing its replication rate. Then, a virus resistant to said drug has been isolated. This virus has been inoculated in mice, showing that the survival rate after infection is high. At higher survival rates, they have been shown to generate a good immune response against RVFV.
To propose this new mutant as a vaccination strategy, it is necessary to verify whether its replication machinery, polymerase, is high fidelity. This characteristic affects the sense that the virus is attenuated because genetic diversity will not be generated and the elderly because it makes the virus stable. Therefore, now the objective is to study the virus replication rate. If the rate is lower than virulent viruses, then the premises necessary to propose this virus as a vaccine candidate would be met, since it is immunogenic, non-virulent and genetically stable over time.
For this purpose, massive sequencing will be applied to be able to study the variation in the polymerase fidelity rate. The experience of IRTA-CReSA in techniques for characterizing mutations by massive sequencing of the swine flu virus will help this purpose.