African horsesickness: pathogenesis and immunity.

This research investigates African horsesickness (AHS), detailing its pathogenesis, immunity, and the impact of virus virulence on disease expression in horses. It also discusses protective antibodies and their relevance to vaccination.

Understanding African Horsesickness

• African horsesickness (AHS) is a severe disease affecting horses and other equines, caused by an orbivirus transmitted by arthropods. This virus belongs to the Reoviridae family. It is important to note that this disease is non-contagious, meaning it does not spread from one horse to another through direct contact.

Clinicopathologic Syndromes

• AHS presents in three notable clinicopathologic syndromes in horses, including pulmonary (affecting the lungs), cardiac (affecting the heart), and a fever form of the disease. All forms are severe and pose a significant threat to equine health.

The Role of Virus Virulence

• The research highlights that the stipulated form of AHS expressed in naive horses is primarily determined by the virulence of the virus inoculum. The virulence refers to the potency of the virus, i.e., its ability to infect and cause harm. Higher virulence leads to more severe disease.

Immunity from AHS

• Horses that recover from AHS exhibit robust humoral immunity against subsequent infections with similar strains of the virus. Humoral immunity refers to immunity mediated by antibodies generated by B cells in animals (including humans). This form of immunity is critical in defending against outside pathogens.

Protective Antibodies

• The antibodies responsible for this protective immunity appear to target neutralizing epitopes on the outer surface (VP2) of the AHS virus. Neutralizing epitopes are segments of the virus, recognized by the immune system, which can be targeted by antibodies to neutralize the virus and prevent infection.

Vaccination Implications

• This study paves the way for a discussion about the relationship between neutralizing these viruses and developing an effective AHS vaccination. If a vaccination can tutorialize the immune system to produce antibodies against these neutralizing epitopes, it could potentially prevent horses from contracting AHS altogether.