Ognjen Stevančević

Research of immune response in unvaccinated piglets against porcine circovirus type 2.

Infection of pigs caused by porcine circovirus type 2 (PCV2) is present throughout the world. The aim of this study was to determine, based on the follow-up of the class IgG titers in piglets and fattening pigs, the duration of colostral immunity against infections in pigs caused by PCV2. The study included 28 piglets, whose titer was determined by using indirect ELISA test in intervals up to 110 days of age. The observed average values of IgG in piglets aged 21 days (8.47 log2) and 35 days (6.69 log2) in our surveys indicate very high titers of maternal antibodies, and that the piglets at this age are, to some extent, protected from infection caused by PCV2. Absence of the specific anti PCV2 antibodies was determined in 14.29% (21 days old) and 15.38% (35 days old) piglets at this age. The average titer of antibodies, specific for PCV2, in blood serum of piglets on the 50th day decreased to 3.74 log2, what indicates that in the majority of piglets (61.54%) catabolism of colostral antibodies occurred. On the 80th day of the piglets life there were no seropositive specimens, which unambiguously indicates that in this age, there was a complete catabolism of colostral antibodies and the disappearance of passive immunity. In all the 110 days’ old fattening pigs, an average antibody titer recorded a sharp rise (12.78 log2). Possible reasons for this sudden increase in PCV2 antibody titers in the blood serum of fattening pigs is is a widespread presence of this infection in our region, as well as the fact that there exists a part of pigs population which is not immune to PCV2 infection. The results of this research are important for choosing the optimal moment for vaccination, considering that high titers of colostral antibodies of class G on the 21st and 35th day of piglets’ life have been proven. This data points out to a possible interference with vaccine immunogens in the case of vaccination in this particular age.

Investigations of significance of blood smear results in diagnostics of infectious and parasitic diseases in dogs

The microscopic examination of stained smears of peripheral blood is of vital significance in the speedy diagnostics of infectious and parasitic diseases, in particular during the stage of infection when the cause is present in the blood, or blood cells. It is sometimes possible to make a definitive diagnosis of an infectious or parasitic disease following an examination of a stained smear of the peripheral blood. Since microscopic examinations of a peripheral blood smear are applied increasingly rarely in clinical practice, due to the development of other methods for the diagnostics of infectious and parasitic diseases in dogs, as well as the lack of knowledge of the morphology of the numerous causes that can be present in the blood, we carried out an investigation into the presence and spread of infections whose causes can be present in dog blood. The investigations covered 100 dogs from which peripheral blood smears were taken and then stained with a Giemsa solution according to the standard protocol and examined under a microscope with an immersion lens. The examination of peripheral blood smears stained according to Giemsa resulted in the identification of the presence of an Ehrlichia spp. morula in a neutrophil granulocyte in one dog. The presence of hemotropic mycoplasmas was established in erythrocytes of eleven dogs, while the presence of the protozoa Babesia canis in erythrocytes was identified in five dogs included in the investigations. A microscopic examination of dog peripheral blood smears stained according to Giemsa was shown as a speedy, practical, simple, and inexpensive method for making a definitive etiological diagnosis of these infections, and it should be included regularly in standard protocols for the diagnostics of infectious and parasitic diseases.