Effect Of PGM-CSF/SS DNA Vaccine On Growth And Reproduction As Well As It's Biosafety In Female Mice

The pGM-CSF/SS was a previously constructed DNA vaccine against somatostatin (SS) in our laboratory. Its effect on growth and reproduction and its biosafety were studied in this paper using 45 female mice aged 5 weeks. Mice were orally administered with pGM-CSF/SS plasmid that delivered by attenuated Salmonella CSO22, attenuated Salmonella,and PBS (control group) respectively. Techniques such as PCR, ELISA, plasmid extraction and RIA were used to detect gene intergration,antibodies against SS, levels of estradiol and progesterone respectively. The results were shown as follows:1 The effect of pGM-CSF/SS immunization on growth of female miceThe weight gain in immunized groups was found significantly different compared to the other two groups (p<0.05) at week 2 after the primary and the booster immunization and at week 2 after booster immunization. No significant difference was observed in control and vaccine free groups (p>0.05). This indicated pGM-CSF/SS could promote the growth of immunized female mice.2 Level of antibodies against SSThe antibodies against SS in immunized mice were found significantly different compared to the control groups (p<0.05) at week 2 after the primary and the booster immunization, week 4 after booster immunization and at the time of pregnance. There were not significant difference among SS immunized groups and the other groups after 3 weeks of lactation (P>0.05). The level of antibodies in SS group showed a trendency of increase and reached the peak at week 4 after immunization. But the level of antibodies decreased gradually after parturition, which showed no significant difference with control group 3 weeks after parturition. pGM-CSF/SS gene vaccine can result a high level of humoral immune reaction, which will last for a certain period of time.3 The effect of pGM-CSF/SS immunization on reproductive characteristics of female miceThe vaccine group had significantly shorter estrous cycle than other two groups. However, the results about litter size, individual birth weight and birth weight per litter showed no significant difference among three groups (P>0.05). These indicated that pGM-CSF/SS had no significant effect on the litter size, individual birth weight and birth weight per litter, except for shorteninging the estrous cycle.The levels of estradiol and progesterone were examined at the day of partuition. The result showed that the estrogen level was higher in vaccine group than that in other two control groups (p<0.05). Three weeks later, estrogen level decreased in all three groups. And the difference was not significant between the vaccine group and the other two groups. .However, progesterone level in vaccine group was not significant different than in other groups at the day of partuition and three weeks later(P>0.05). These results indicated that pGM-CSF/SS could affect the estrogen level, but have no effect on progesterone.4 The effect on the growth of the offspring miceWe examined the weight gain of offspring mice during lactation period. The weight gain in vaccine group was significantly higher than that of the other two groups at the end of the first week and the second week after laboring(p<0.05). However, at the end of lactation period, the difference in weight gain in offspring mice was not significant among three groups(P>0.05). These indicated that the vaccine had limited effect on the ability of lactation. After lactation period, there was no significant difference of weight gain among the offspring mice.We also examine the level of antibodies against SS and growth hormone of offspring mice. Compared to the pGM-CSF/SS free group and the control, the level of antibodies against SS and growth hormone was higher in vaccine group but not significant(P>0.05). This was in agreement to the weight gained .These results showed that pGM-CSF/SS had limited enhancement of growth of offspring mice.5 studies on reproductive toxicity and gene integration of DNA vaccineComparing the experimental groups with control,there were no difference in Utter size,birth weight per litter,individual birth weight,male/feale of offspring and every organ index in female mice and their offsprings(P>0.05),and there was no malformation and death in offspring. SS DNA vaccine immunization had not bad effect on mice reproduction and their offspring's growth and develepment. No plasmid was detected in all the tissues of mother mice and their musculus, and no integration was found in the investigated tissues. These results indicated that the pGM-CSF/SS delivered by attenuated Salmonella was biosafe.