Characterization of African horsesickness virus serotype 4-induced polypeptides in Vero cells and their reactivity in Western immunoblotting.

This research explores the different proteins, or polypeptides, created by the African horsesickness virus serotype 4 (AHSV-4) in infected cells. It identifies which proteins generate significant antibodies in horses, either from natural infection or vaccination, and notes that some proteins are conserved across various versions of the virus, being useful for diagnosis.

Description of observed proteins

• The researchers studied the proteins produced by the African horsesickness virus serotype 4 (AHSV-4) in infected Vero cells (a lineage of cells used in cell cultures).
• Through comparison with non-infected cells and using a process called SDS-PAGE (a method used to separate proteins based on their electro mobility), they identified 22 virus-induced proteins.
• Out of these, seven were identified as structural proteins, which are components of the virus particle itself. This included four major structural proteins (VP2, VP3, VP5 and VP7), and three minor ones (VP1, VP4 and VP6).
• Four other proteins, termed ‘non-structural’, were not part of the virus particle but were produced in infected cells. These are presumably involved in the infection or replication process of the virus, and were named P58, P48, P21 and P20 based on their molecular weights.

Immune Response and Reactivity Studies

• The study was aimed towards the understanding of which proteins generated a significant antibody response in horses, whether through natural infection or vaccination.
• Results from radioimmunoprecipitation and immunoblotting assays showed that three structural proteins (VP2, VP5 and VP7) and the four non-structural proteins (P58, P48, P21 and P20) primarily induce these immune responses.

Significance for Diagnosis and Cross-reactivity

• The team also checked for cross-reactivity between AHSV-4 and sera from horses experimentally infected with seven other serotypes (different strains of viruses within the same family).
• The proteins VP5, VP7, P48, P21 and P20 were found to be ‘conserved’ – meaning that they are common to all eight tested serotypes.
• This implies that these proteins could be used to diagnose the infection of any of these eight serotypes, making them valuable markers for detecting the presence of the disease.