Competence of mosquitoes native to the United Kingdom to support replication and transmission of Rift Valley fever virus.
BACKGROUND
Rift Valley fever phlebovirus (RVFV) is a mosquito-borne arbovirus causing severe disease in humans and livestock. It is endemic in Africa and spread to the Arabian Peninsula in 2000 raising concerns it could emerge in Europe. The ability of temperate mosquitoes from the United Kingdom (UK) to support replication and transmission of RVFV is unknown.


METHODS
In this study, two colonised lines of Culex pipiens, wild-caught Aedes detritus and Ae. rusticus from the UK were infected with pathogenic strains of RVFV to assess their vector competence. Mosquitoes were offered artificial blood-meals containing 106 or 107 plaque forming units (PFU)/ml RVFV, simulating natural peak viraemia in young ruminants, and maintained at 20 °C or 25 °C for up to 21 days. Bodies, legs and saliva were collected and tested for the presence of viral RNA and infectious virus to determine the infection, dissemination and transmission potential.


RESULTS
Across temperatures, doses and strains the average infection, dissemination and transmission rates were: 35, 13 and 5% (n = 91) for Cx. pipiens (Caldbeck); 23, 14 and 5% (n = 138) for Cx. pipiens (Brookwood); 36, 28 and 7% (n = 118) for Ae. detritus. However, despite 35% (n = 20) being susceptible to infection, Ae. rusticus did not transmit RVFV. Survival of Aedes species was negatively affected by maintenance at 25 °C compared to the more representative peak average British summer temperature of 20 °C. Increased mortality was also observed with some species infected with 107 PFU/ml compared to 106 PFU/ml.


CONCLUSIONS
It can be concluded that temperate mosquito species present in the UK demonstrate a transmission potential for RVFV in the laboratory but, even at high temperatures, this occurred at low efficiency.
['Lumley|Sarah|S|0000-0002-8605-3650', 'Hernández-Triana|Luis M|LM|', 'Horton|Daniel L|DL|', 'Fernández de Marco|Maria Del Mar|MDM|', 'Medlock|Jolyon M|JM|', 'Hewson|Roger|R|', 'Fooks|Anthony R|AR|', 'Johnson|Nicholas|N|']
D000330:Aedes D000818:Animals D003465:Culex D006801:Humans D000072138:Mosquito Vectors D012295:Rift Valley Fever D012296:Rift Valley fever virus D012463:Saliva D012621:Seasons D013696:Temperature D006113:United Kingdom
Mosquito Rift Valley fever virus Arbovirus UK Vector competence