Ultrastructural Insight into Rift Valley Fever Virus Pathogenesis in Different Human Cell Types

Rift Valley Fever Virus (RVFV) is an arbovirus that predominantly affects sheep, goats, and cattle, causing epizootics in livestock and epidemics in humans. Infection in pregnant livestock leads to high abortion rates and neonatal mortality. In humans, RVFV usually causes a self-limiting febrile illness, but severe forms can develop, such as hepatitis, hemorrhage, encephalitis, and death. In addition, the association between RVFV infection during pregnancy and miscarriages or stillbirths has been documented. RVFV is transmitted by a range of mosquito species, and, due to the diffusion of these insects, the virus has spread in several world regions, making possible the risk of a public health emergency. Nevertheless, research remains limited and cellular pathology is still poorly characterized. This work aimed to fill some knowledge gaps on the comprehension of RVFV pathogenesis. For this purpose, transmission electron microscopy (TEM) was used to analyze cellular modifications associated with RVFV morphogenesis in four human cell lines (HuH-7, LAN-5, A549, and HTR-8/SVneo) derived from liver, brain, lung, and placenta. Our results showed that all four cell lines are permissive to RVFV infection and highlighted differences in the cytopathogenesis associated with the cell type. These findings could have important implications in understanding disease mechanisms and developing antiviral strategies.