HYPERGLOBULINEMIA AND LYMPHOCYTE SUBSET CHANGES IN NATURALLY INFECTED, INAPPARENT CARRIERS OF EQUINE INFECTIOUS-ANEMIA VIRUS

Objective-To determine blood protein concentration, immunoglobulin con centration, and lymphocyte profiles in equine infectious anemia virus (EIAV) seropositive, naturally infected horses without clinical signs of disease. Animals-26 clinically normal seropositive horses, 6 febril e ponies with experimentally induced EIA, and 52 clinically normal ser onegative horses and ponies.Procedure-Serum and EDTA-anticoagulated bl ood were obtained from all horses and ponies, and total serum protein and albumin concentrations, immunoglobulin concentrations, and blood l ymphocyte subset counts were determined. Results-Compared with seroneg ative horses, EIAV seropositive inapparent carrier horses had no signi ficant difference in serum reverse transcriptase activity, PCV, or pla telet count. Inapparent carrier horses had increased plasma total soli ds and serum globulin concentrations and decreased serum albumin conce ntration and albumin-to-globulin ratio. Total serum immunoglobulin and serum IgM concentrations were increased. Inapparent carrier horses ha d significantly decreased percentages of CD5(+) and CD4(+) blood lymph ocytes. Conclusions-Serum protein and lymphocyte subset changes in EIA V-infected inapparent carrier horses are consistent with immune activa tion or chronic inflammation , both of which may, in part, be the resu lt of virus-induced polyclonal B-cell activation. Clinical Relevance-E IAV seropositive horses have immune-related abnormalities consistent w ith ongoing viral activity regardless of the duration they have been i nfected, even when the usual signs of disease (anemia, fever, weight l oss) are not apparent.