CReSA carried out for the first time an experimental infection of sheep with Rift Valley fever virus (RVF) in the level-3 biocontainment facilities of this center in 2009. Subsequently, CReSA takes part at ENCRAD (European Network for the Coordination of Rift Valley fever Animal experimentation and Diagnostic).

The kick off meeting of ENCRAD (European Network for the Coordination of Rift Valley fever Animal experimentation and Diagnostic) was celebrated in Amsterdam, May 12th with the participation of Dr Xavier Abad (BSL3 Laboratory Manager of CReSA). ENCRAD will allow the compilation of data on animal experimental infections, sharing expertise, reagents, and procedures among participants.

RVF is a viral zoonosis that primarily affects animals but also has the capacity to infect humans. Infection can cause severe disease in both animals and humans. The disease also results in significant economic losses due to death and abortion among RVF-infected livestock. RVF shows episodic outbreaks in Sub Saharan countries, Egypt and the Arabian Peninsula eventually associated to climatic conditions. The disease is caused by an arbovirus competent in many mosquito species present in most European countries. Many European regions have optimal habitats in which the virus could persist in the event of an unwanted introduction of the virus within European boundaries.

Increasing our understanding of the disease is therefore highly desirable to increase our preparedness to fight this important disease. The study carried out by the researchers of the CReSA in the level-3 biocontaintment facilities (BSL3) of the center tried to establish a reproducible infection model of RVF in a European sheep breed.

Working on RVF in BSL3 laboratories.

Groups of 4 sheep of 6-8 weeks old were inoculated subcutaneously with 105 TCID50 of each isolate. The following tests were carried out:

• Viremia titers were estimated by real time PCR and presence of viable virus confirmed by virus isolation.
• Different tissues were analysed for specific pathological changes by histopathology and/or immunhistochemistry.
• Shedding of RVFV and horizontal transmission to non-infected, in contact lambs was also investigated.

The main results were:

• None of inoculated lambs died.
• All infected lambs except one develop pyrexia and viraemia at day 2 post-inoculation.
• No other clinical signs were observed except for three lambs presenting blue eye (corneal opacity) no concomitant with their viraemia windows.
• Viraemia (tracked by Real-Time PCR) lasted for 2 to 4 days with the sole exception of two lambs which kept viraemic along the whole study.
• Viral RNA copies from nasal and oropharingeal swabs were detected just one day later the starting of viraemia, lasting no more than 5-6 days, and somewhat inconstant in their viral loads.
• One in-contact non inoculated lamb became infected with a delay of two days, showing pyrexia and viraemia. Transmission of virus in absence of arthropod vector is, so, possible.

These results were presented by Dr. Mariano Domingo as an oral communication (An experimental infection of European breed sheep with Rift Valley fever virus. Francesc X. Abad, Nuria Busquets, Fernando Rodriguez, David Solanes, Mariano Domingo and Alejandro Brun) in the 3rd Annual Meeting EPIZONE (12-15 May 2009, Antalya, Turkey) and by Dr. Xavier Abad in 5th European meeting on Viral Zoonoses. (26-29 September 2009, Saint Raphael, France).

To contact with the researcher in charge of these studies:

Dr. Nuria Busquets
Researcher
Email: nuria.busquets@cresa.uab.cat
Telephone no.: +34 93 581 4342
Fax: +34 93 581 44 90
Edifici CReSA. Campus UAB
08193 Bellaterra (Barcelona) Spain

To know more about RVF(WHO):

http://www.who.int/mediacentre/factsheets/fs207/en/index.html