species further, the S segment, that is coded by the nucleocapsid protein, and the L polymerase function together to create a replication of the viral genome. Due to this, one segment will restrict the molecular evolution of another segment and this is said to be inherited as a pair. On the contrary, the M segment codes for viral glycoproteins and these could be more prone to mutations due to a higher selective pressure in their coding region because these proteins are major host range determinants. Pathogenesis There is not a significant amount of information about regarding the natural pathogenesis of OROV infections because there have been no recorded fatalities to date. It is known that within 2–4 days from the initial onset of systematic symptoms in humans, the presence of this virus is detected in the blood. In some cases this virus has also been recovered from the cerebrospinal fluid, but the route of invasion to the central nervous system remains unclear. To further understand the pathogenesis of how this virus manifests in the body experimental studies using murine models have been performed. Murine Models BALB/c neonate mice were treated with this virus subcutaneously and presented clinical symptoms five days after inoculation. The mice revealed a high concentration of the replicating virus in the brain along with inflammation of the meninges and apoptosis of neurons without encephalitis, which is inflammation of the brain due to an infection. These findings confirmed the neurotropism of this virus, which means that this virus is capable of infecting nerve cells. Immunohistochemistry was used to reveal how this virus had access to the central nervous system. The findings indicated that the OROV infection starts from the posterior parts of the brain and progresses toward the forebrain. The oropouche virus spreads through the neural routes during early stages of the infection, reaching the spinal cord and traveling upward to the brain through brainstem with little inflammation. As the infection progresses, the virus crosses the blood-brain barrier and spreads to the brain parenchyma leading to severe manifestations of encephalitis. Damage to the brain parenchyma can result in the loss of cognitive ability or death. Diagnosis Diagnosis of the oropouche infection is done through classic and molecular virology techniques. These include: Virus isolation attempt in new born mice and cell culture (Vero Cells) Serological assay methods, such as HI (hemagglutination inhibition), NT (neutralization test), and CF (complement fixation