| Abstrakt: |
The RC/79 strain of the Aujeszky's disease virus was able to induce reproductive failure of pregnant gilts intranasally inoculated at different gestation periods. Four gilts 40-46 days pregnant (group A) and 6 gilts 70-73 days pregnant (group B) were instilled with 0.2 ml x 10(5) tissue culture infectious dose 50 (TCID50/0.2 ml) of the RC/79 strain into each nostril. Two gilts 70-73 days pregnant (group C) were used as non exposed controls. The three groups were kept in separated boxes and they were observed for clinical signs of infections and samples were collected for determination of viral shedding every day. Viral isolation was attempted in Vero cells (figure 1). From the 2nd to 7th day after inoculation, groups A and B showed fever anorexia, sneezing, coughing and depression; and viral isolation from nasal swabs was possible in 7 gilts at days 4 to 11, 9 gilts developed neutralizing antibodies. The virus caused fetal reabsorption in swine during the first period of pregnancy (group A), while infection during late pregnancy resulted in still birth or normal pigs and one mummification (group B). The entire a live litter was composed of no more than 8 suckling pigs in both groups. At necropsy virus from turbinates, ovary , placenta, spleen and lung could be isolated only from 3 gilts (group B, table 1). In 5 of 35 stillbirth and alive fetuses virus could be isolated from spleen (100%), lung (80%), liver (60%) and brain (40%) indicating that the virus has the ability to cross the placental barrier thus producing lesions in porcine fetuses and causing reproductive failure in sows (table 2). Tissue specimens from these 35 fetuses were fixed in 10% formalin, included in paraffin sectioned and stained with hematoxylin and eosin. In 13 fetuses microscopic lesions i.e. necrotic foci were found in lung (60%), liver (40%) and spleen (20%), these alterations were coincident with gross lesions in most of them. Inclusion bodies were absent. The gilts organs did not present gross lesions. |
