IMMUNOLOGICAL AND HISTOPATHOLOGICAL STUDY OF THREE TYPES OF ANTIGENS FROM S. PSEUDINTERMEDIUS

This study aimed to aims to prepare three types of antigens from S. pseudintermedius, Staphylococcus was isolated and identify the Staphylococcus species from otitis externa samples of dogs as well as from the tonsillitis, rhinosinusitis and skin lesion so human. Including. The collection of 100 samples involved 50 from humans and 50 from dogs from different location in Baghdad governorate during November (2021)to March (2022).the samples were cultured on Mannitol salt agar, purified, and identified according to colony morphology, Gram stain, and biochemical tests. The bacterial isolates were confirmed by VITEK technique. The results showed that 35out of 50 dog samples were positive for Staphylococcus while 27 out of 50 human sample were positive. Prepare three types of antigens from S. pseudintermedius which considered the most prominent isolate in this study ,and their immunogenic activity was evaluated by cellular immunity study. For this purpose, twenty rabbits randomly divided into four groups (five animals in each group) the first group was immunized with (WSAg) 32/mg subcutaneously, the second group was immunized with (peptidoglycan)25mg/ml subcutaneously, the third group was immunized with (cell wall )35mg/ml subcutaneously, the fourth group was injected by PBS (pH7,2) as a control group. The cellular skin reaction was observed by using WSAg in delayed hypersensitivity (DTH) skin test at 21days post first immunization. the result of skin test shows appearance of erythematic and skin thickness among all the three immunized groups while no positive skin reaction occur in the control group after 24 and 48 hours post examination. The challenge dose was given for all groups at day 28 post first immunization. after Challenge dose animals wereobservedclinicaly.one animal of control group was died 48 hrs after challenge dose. The other control group animals show signs of illness. All animal groups were scarified after 7 days of challenge dose and the Histopathological study show a pathological changes in control group that indicate a severe infection with Listeriosis, this supported by appositive isolation of L. monocytogenes .all immunized groups show different cellular immune response characterized generally by aggregation of mononuclear cells and other inflammatory cells in internal organs with negative bacterial isolation