Study On Effects Of The Oral Somatostatin Gene Vaccine On Immunity In Intestine Of Mice

The plasmid pcDNA3.1-HBs/SS was transformed into an attenuated S.typhimurium strain SL7207, resulting in oral Somatostatin (SS) gene vaccine. The bacteria lyses quickly after immunization, it can express HBsAg/SS protein, produce SS antibody which neutralize the inhibition of SS, so the SS gene vaccine can promote growth. The vaccine has characteristics of cheap costs, convenience and safety which can be widely generalized. The purpose of this study was to examine the effect of this SS gene vaccine on growth and immunity in intestine, also including the safety and the distribution of bacteria.Safety test of SS gene vaccine: thirty 4-week-old female healthy mice were divided into treatment group I, treatment group II and control group. Treatment group I was immunized with vaccine by digestive rout with 10~9CFU per mouse , Treatment group II was immunized with 10~8CFU per mouse, and control group was immunized with PBS. The mice were observed 15 days, some mice were killed 1 week after immunization. The result showed treatment group II have no side effects, no pathological changes were observed in viscera. The results suggested the SS gene vaccine was safe at dose of 10~8CFU per mouse.150 4-week-old female healthy mice were divided into 3 treatment groups, groups were immunized by digestive rout. Treatment group I was boosted after 2 and 4 weeks after first immunization. Treatment group II was boosted after 2 and 3 days after first immunization. Control group was immunized with PBS.Distribution of attenuated salmonella: two mice were killed at different times in 8 days after first immunization, the sample of jejunum, liver and spleen were dyed using Giemsa's fluid and the bacteria were observed. The results showed that the number of bacteria in jejunum reached the highest level at 16-20h and then declined, the bacteria in spleen were observed at 4 days after immunization, no bacteria had been observed in liver. The results suggestted some bacteria had been decomposed in intestine, some had been transformed to secondary lymph organs by macropahages and then induced both local mucosal cellular...