Immunohistochemical identification of the bacterial antigen of Aeromonas hydrophila in the kidneys and spleen of carps and evaluation of the activity of kidney phagocytes after intraperitoneal and immersion immunization

Abstract

The aim of this study was to evaluate the activity of kidney phagocytes after immunization of fish with inactivated bacteria of Aeromonas hydrophila and to determine the location and permanence of the bacterial antigen in the lymphoid organs, the kidney and the spleen, of carps immunized intraperitoneally (group I) and by immersion (group II) at 12oC. We examined the absorption of bacteria by kidney leucocytes (PK%), the killing capacity of phagocytes (IB) and chemiluminescent activity (CL). Evaluations were performed 12 h, as well as 3, 7, 14 and 28 days after immunization. At all these time points, the values of the parameters examined were higher in fish immunized intraperitoneally than in those immunized by immersion. The absorption of bacterial cells by kidney phagocytes was particularly high after 14 days after immunization in fish group I whereas their killing and chemiluminescent activity was particularly high in 7 days after immunization in group I. Immunohistochemical examination revealed an extensive distribution and large amounts of the antigen in the interstitial part and melanomacrophage centers of the kidneys and spleen after the intraperitoneal administration of the antigen, By contrast, small amounts of the antigen were found in these organs after it had been administered by immersion.