Hyperglobulinemia and lymphocyte subset changes in naturally infected, inapparent carriers of equine infectious anemia virus.

The research aims to analyze the impact of equine infectious anemia virus (EIAV) on blood protein concentration, immunoglobulin concentration, and lymphocyte profiles in horses that are infected but do not show any clinical signs of the disease.

Methodology

• The study conducted a comparative analysis between different groups of horses: 26 healthy seropositive horses, 6 febrile ponies with EIA induced experimentally, and 52 healthy seronegative horses and ponies.
• Blood samples were obtained from all participants, and various measurements were taken. These included total serum protein and albumin concentrations, immunoglobulin concentrations, and blood lymphocyte subset counts.

Results

• There was no significant difference in serum reverse transcriptase activity, PCV, or platelet count between seronegative and seropositive EIAV horses.
• However, the group of seropositive horses, which are carriers of the virus but do not show any symptoms (inapparent carriers), demonstrated higher plasma total solids and serum globulin concentrations, decreased serum albumin concentration, and reduced albumin-to-globulin ratio.
• Moreover, these inapparent carriers also had increased total serum immunoglobulin and IgM concentrations as well as reduced percentages of CD5+ and CD4+ blood lymphocytes.

Conclusions

• Changes in serum protein and lymphocyte subsets in EIAV-infected inapparent carrier horses are consistent with immune activation or chronic inflammation. These changes may be due, in part, to virus-induced polyclonal B-cell activation.
• Despite the absence of usual signs of disease such as anemia, fever, and weight loss, EIAV seropositive horses exhibit immune-related abnormalities suggesting ongoing viral activity, irrespective of the length of infection.

These findings underscore the importance of regular testing for EIAV in horses, even if they show no visible signs of infection, to prevent widespread transmission of the virus.