Studies On The Distribution And The Pathological Changes In Sheep Infected By Gansu Popular Strains Of The Sheeppox Virus Artificially

Sheeppox, caused by Sheeppox virus (SPV), is an acute and highly contagious disease.The typical feature is the pox lesions in the ski、mucosa and alimentary tract. Due to its high morbidity and mortality, more and more researchers begin to pay more attention to sheeppox virus research at home and abroad.This experiment got12sheep divided into A, B groups, group A only10sh eep, as the experimental group;Group B only2sheep, as the negative control grou p.This experiment used Gansu popular strains of the sheeppox virus to infect expe rimental group artificially by intradermal inoculation way. At the same time, the n egative control group were infected by physiological saline.We randomly killed tw o sheep after infection at4d、6d、8d、10d、12d respectively.The clinical symptom s、anatomical changes、histopathology and cellular pathology were observed and t he indirect in situ PCR method was used to detect the pathogenic distribution in all organizations.The clinical symptoms observation showed that there were pea-sized circular skin erythema in tail root、abdominal bare skin place at post-infection4days. The elevated temperatures reached41.5℃; At post-infection5days, eye conjunctiva congested and plenty of mucus was in nose;At post-infection8days, some erythema becomed white papules; At post-infection10days,,the papules becomed blister and part of the blister bursted in tail root of sheep.At post-infection12days, a little broken blister festered in the tail root.The blister which was’t broken dried and scabed gradually.The histopathological observation showed that at post-infection4days, all organs including heart, liver, spleen, lung, kidney, lymph nodes and so on had no obvious histopathological changes. At post-infection6days, the epithelial cells of skin appeared edema and the tissue gap widened.At post-infection8days,the sheep pox virus inclusion body can be seen in the cytoplasm in the epithelial spine skin layer cells of the skin.The skin epithelial cells appeared parakeratosis. The liver appeared vacuoles degeneration.At post-infection10days,The epithelial cell of lung appeared hyperplasia,The epithelial cell of alveolar wall in lung becomed cuboidal.The heart appeared myocarditis.At post-infection12days,The lung tissues appeared fibrinous necrotizing pneumonia, a large number of neutrophils、macrophages and lymphocytes infiltrated and blood clots appeared.Ultrastructural pathology observation showed that at post-infection8days, a1arge number of ovoid sheep pox virus particles were in the cytoplasm of epithelia1cells of the skin.Themitochondria of the skin epithelial cells swelled and expand ed.The mitochondrial cristae fallen off and even the entire mitochondria becomed vacuolated.The endoplasmic reticulum of the skin epithelial cells swelled,The Gol gi apparatus appeared expansion.Plenty of ovoid sheep pox virus particles appeare d in the cytoplasm of the epithelial cells of the lung.The mitochondria of alveolar wall epithelial cells swelled and expanded.At post-infection10days, There were a small numbers of sheeppox virus particles in the mitochondria of the skin epith elial cells.The chromatin of Pulmonary macrophage condensed,Golgi apparatus sw elled and expanded extremely.The in situ PCR detection observation showed that there was no positive signal at4days post-infection; Positive signals firstly appeared in the skin while the other tissues were no positive signals at6days post-infection; Positive signals appeared in the lung、 rumen、duodenum and jejunum at8days post-infection; Positive signals appeared in the liver、tongue and ileum at10days post-infection; Positive signals appeared in the heart at12days post-infection; No positive signals appeared in the intestinal lymph nodes and brain during the whole infection.Through histopathological staining and transmission electron microscopy obser vation and indirect in situ PCR methods for this experiment, all results showed t hat there was positive correlation between the distribution of sheeppox virus in sh eep and the pathological damages. All experimental results can provide a theoretic al basis for the further studies on sheeppox virus pathogenesis,and will be helpful for prevention.