RVFV Infection in Goats by Different Routes of Inoculation.

Valerie Smid,Hana Weingartl,Brad Collignon,Carissa Embury-Hyatt,Oliver Lung,Estella Moffat,Andrea Kroeker,Robbin Lindsay

doi:10.3390/v10120709

Abstract

Rift Valley fever virus (RVFV) is a zoonotic arbovirus of the Phenuiviridae family. Infection causes abortions in pregnant animals, high mortality in neonate animals, and mild to severe symptoms in both people and animals. There is currently an ongoing effort to produce safe and efficacious veterinary vaccines against RVFV in livestock to protect against both primary infection in animals and zoonotic infections in people. To test the efficacy of these vaccines, it is essential to have a reliable challenge model in relevant target species, including ruminants. We evaluated two goat breeds (Nubian and LaMancha), three routes of inoculation (intranasal, mosquito-primed subcutaneous, and subcutaneous) using an infectious dose of 107 pfu/mL, a virus strain from the 2006–2007 Kenyan/Sudan outbreak and compared the effect of using virus stocks produced in either mammalian or mosquito cells. Our results demonstrated that the highest and longest viremia titers were achieved in Nubian goats. The Nubian breed was also efficient at producing clinical signs, consistent viremia (peak viremia: 1.2 × 103–1.0 × 105 pfu/mL serum), nasal and oral shedding of viral RNA (1.5 × 101–8 × 106 genome copies/swab), a systemic infection of tissues, and robust antibody responses regardless of the inoculation route. The Nubian goat breed and a needle-free intranasal inoculation technique could both be utilized in future vaccine and challenge studies. These studies are important for preventing the spread and outbreak of zoonotic viruses like RVFV and are supported by the Canadian-led BSL4ZNet network.

Highlights

Rift Valley fever virus (RVFV) is a zoonotic mosquito-borne virus that causes acute infections in ruminants such as goats, cattle, sheep, and camels
94.6–97.75% at the nucleotide level (Figure 1D). We found this sequence homology to be of significance, in that any differences between this study and our previous study with Boer goats and the ZH-501 strain is likely more attributable to the goat breed or the inoculation method than the virus strain
We have previously established the necessary dose required for infection [35] and have demonstrated that mosquito cell-derived virus leads to more consistent viremia compared to the mammalian cell-derived virus [35]

Summary

Introduction

Rift Valley fever virus (RVFV) is a zoonotic mosquito-borne virus that causes acute infections in ruminants such as goats, cattle, sheep, and camels. RVFV outbreaks in livestock are thought to be primarily transmitted by infected mosquitos. Studies have shown that RVFV epidemics typically follow periods of heavy rainfall conducive to large mosquito populations [8,9,10,11] as well as the trade and importation of infected animals into. In Africa, RVFV is mainly transmitted by the Aedes aegypti mosquito, a growing number of studies have made it clear that other mosquito species present in Asia, Europe and North/South America are experimentally competent as RVFV vectors [13,14,15]. If RVFV were to be introduced into other continents and their endemic mosquito populations, it could cause widespread epidemics and could seriously impact the health of human populations and economically important livestock herds

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Conclusion