Expression of E2 (Gp 55) Glycoprotein of Classical Swine Fever Virus in Lymphoid Tissue and Brain of Experimentally Infected Piglets with Different Immunological Status

Abstract

Classical swine fever (CSF) is a highly contagious viral disease of domestic swine and wild boars. The aim of the study was to examine samples of lymphoid tissues and brain for the presence of Classical Swine Fever Virus (CSFV) antigen in piglets that originate from vaccinated and unvaccinated sows, in order to compare the intensity of pathological lesions in conditions of different immunological status. A total of 20 crossbreed piglets of both sexes, aged 45 days were divided in three groups (G1, G2 and G3). Piglets of G1 originated from sows vaccinated with a live vaccine containing attenuated C strain CSFV. Piglets of G2 originated from unvaccinated sows. Two piglets of G3 originated from vaccinated and two piglets from unvaccinated sows and they served as the control group. All the piglets from G1 and G2 were intramuscularly inoculated with 2×10 5 TCDI/ 50 of CSFV, Baker strain and they died by the 22 nd day post inoculation. Immunohistochemistry was applied for immunolabeling E2 (gp55) glycoprotein of CSFV in the tonsils, mandibular lymph nodes, ileocecal valve and brain of all tested piglets. Differences were observed in the severity of lesions in the lymphoid tissue and the brain between G1 and G2 piglets. The present level of colostral antibodies was not able to protect piglets in G1 from the fatal outcome of the disease. Among others, this fi nding may also have an impact on vaccination policy in the future. Having in mind that vaccination of all domestic pigs with attenuated C-strain vaccine is still a mandatory control measure for CSF in Serbia, soon a non-vaccination policy should be harmonized with EU directives.

Classical Swine Fever: Active Immunisation of Piglets with Subunit (E2) Vaccine in the Presence of Different Levels of Colostral Immunity (China Strain)

“…S1 -S6) exposed to contact infection, pathological lesions characteristic for CSF were not detected. In the control group, the gross pathology lesions were characteristic for the acute course of CSF, which is in accordance with the results of Prodanov et al [8] and Polaček et al [16].…”

“…A completely different result was recorded in group C: the presence of CSFV antigen was not established in organ samples only in piglet No. 16. In all the other piglets from this group, a positive fi nding was established.…”

“…Rectal temperature and mortality were recorded daily. Fever was defi ned as body temperature higher than 40°C [13,15,16].…”

“…From the day when 28 piglets from A, B, C groups and D-control subgroup were experimentally infected, blood samples were obtained from the jugular vein of each individual piglet according to the following sampling scheme: 0, 2, 4,6,8,10,12,14,16,18,20,22,24,26, 28 days post infection (dpi) to detect the presence of antibodies against CSF, viremia and viral RNA (ELISA test and RT-PCR). The control of CSFV shedding by vaccinated, artifi cially infected piglets was performed by RT-PCR analysis of oropharyngeal and rectal swabs with the following sampling scheme: 0, 2, 4, 6, 8 and 10 dpi.…”

“…By conducting the program of CSF eradication, Serbia approaches the moment when vaccination with C-strain against CSF will be ceased [11,16]. The next phase of the CSF eradication program, might include prophylactic vaccination with the subunit vaccine at the regional level, i.e.…”