Evaluation Of The Efficacy Of The Inactivated Vaccine Of Porcine Circovirus Type2 (WH Strain)-Distribution Of PCV2 In Intestines And Kidney

The infection of Porcine circovirus type 2 (PCV2) can cause many kinds of diseases,which includes Postweaning pigs multisystemic wasting syndrome (PMWS). For the low pathogenicity of PCV2, people didn't pay close attention to the virius. Along with the outbreaks of diseases such as PMWS, PCV2 has been detected all over the world, and the infection rate of pigs beening higher and higher. At the point of prevention and cure, the use of vaccines, which is effective and safe, has been proved the major method. At present, there are no commercial vaccines to be presented to the public.In this study, we compared the histology changes in kidney and intestine between positive pigs challenged and pigs challenged after immunized with vaccine against porcine circovirus type2. The results indicate that, histologicaly, this vaccine can petect pigs from PCV2 effectively, whithout any adverse reaction. The 40 piglets age from 25 to 35 days, fall into 8 groups, each group with 5 pigs. Four groups immunized with 2mLX 107.0TCID50 vaccine intramscular injection in neck, other four groups uninmunized as control. All the work as follow:1. The efficacy of the inactivated vaccine of PCV2 (WH Strain) on kidneyBy the way of Hematoxylin-eosin staining, the study compared pathological changes of kidney between all the groups; By the way of electron microscope, the study compared changes of ultrastructural organization. Results demonstrated that, PCV2(WH stain) may introduce hyperemia of renal glomerulus and destroy intracellular membrane severitily; Positive signals of PCV2 presented on renal tubular epithelial and kidney glomerulus, showing the strong tropism to kindney, which indicated this virus may cause the break out of PDNS. In unchallenged groups, all the tissues detected with PCV2 were presenting with pathological changes. On the other hand, in challenged groups, part of tissues detected with PCV2 weren't presenting with pathological changes, especially challenged after 3 weeks. Which indicated PCV2-WH sain may cause pathological changes in kidney, and the inactivated vaccine have efficacy on kidney, especially challenged after 3 weeks. By the way of electron microscope, we found there were granules unknown, whithing diameter about 80nm, been ptesented in cells in tissues with PCV2. And this indicated that experimental animal may be infected whith other kinds of diseases, or, these granules were specificly formed after vaccine.2. The efficacy of the inactivated vaccine of PCV2 (WH Strain) on intestineBy the way of Hematoxylin-eosin staining, the study compared pathological changes of intestinal tract between all groups; By the way of electron microscope, the study compared changes of ultrastructural organization. Results demonstrated that, PCV2 (WH stain) may introduce enteremia of duodenum, positive signals concentrated on lamina propria of ileum, whith some signals presented in Payer's Patch. All these indicated that this virus may cause diarrhea. Few tissues in unchallenged groups were detected PCV2, which were challenged afer 3 weeks. This indicated that PCV2-WH stain has a weak tropism to intestine, infective stage focused in 1-2 eeks. Pathological changes were presented in duodenum while PCV2 were detected in ileum, which indicated that PCV2-WH stain can't lead pathological changes in intestine directly. At the same time, there was no tissue in unchallenged groups showing pathological changes or PCV2, which indicated the vaccine have efficacy on intestine, and PCV2-WH stain can lead pathological changes in intestine undirectly. Results from electron microscope also presented a severe destroy of intracellular membrane. There were no pathological changes in pigs challenged after immunized with vaccine, which indicated that the vaccine has a satisfactory protection on intestinal tract.3. Changes of apoptosis in kidney and intestinal tract caused by PCV2By the way of TUNEL, the study compared changes of apoptosis among groups. Results indicated that PCV2 may increase apoptosis, which agree to the papers published. All therse indicated that this vaccine has some kind of ability to release the increasing of apoptosis caused by PCV2.