Modulation of Serum Protein Electrophoretic Pattern and Leukocyte Population in Horses Vaccinated against West Nile Virus

SIMPLE SUMMARY: Vaccination is the primary method of reducing the risk of West Nile virus (WNV) infection in horses but clinical disease is not fully prevented. The aim of this study was to evaluate the hematological parameters, including the leukocyte population and the serum protein electrophoretic pattern of horses subjected to two-dose vaccine administration with inactivated WNV. Vaccine-related changes in lymphocytes, neutrophils, monocytes, serum total proteins, α1-, α-2-, β- and γ-globulin fractions are found. ABSTRACT: This study aimed to evaluate the hematological and serum protein electrophoretic profiles of horses after inactivated West Nile virus (WNV) vaccine administration. Blood samples were collected from 10 horses before (T0), after 24 h, 48 h, 72 h, 1 week, 2 weeks and 3 weeks (T1(I), T2(I), T3(I), T4(I), T5(I) and T6(I)) from the first WNV vaccine-dose administration, before the vaccine-booster (TPRE(II)), and after 24 h, 48 h, 72 h, 1 week, 2 weeks and 3 weeks (T1(I I), T2(II), T3(II), T4(II), T5(II), T6(II)) from the WNV vaccine-booster. There was a significant increase in lymphocytes and a decrease in neutrophils after both the first vaccine-dose and vaccine-booster administration compared to the baseline values (p < 0.01). Monocytes showed higher values after 72 h, 1 week and 2 weeks from the vaccine-booster (p < 0.01). Higher serum total protein values were found in horses after both the first vaccine-dose and booster administration (p < 0.05). α1-lobulins increased after the vaccine-booster with the highest levels measured at T4(II) (p < 0.05); α-2- and β-globulin fractions increased throughout the post-vaccine period compared to the baseline values (p < 0.05); and higher γ-globulin values were found before the vaccine-booster (TPRE(II)) and after 24 h, 72 h and 3 weeks from the vaccine-booster (T1(II), T3(II) and T6(II)). The findings allow us to conclude that the WNV vaccine used in the current study does not alter the overall hemogram picture of horses although it is associated with modulation of leukocyte populations and the serum protein electrophoretic pattern.