EFFECT OF ORAL APPLICATION OF KILLED STREPTOCOCCUS MUTANS CELLS ON IMMUNOGLOBULIN- A LEVEL IN ALBINO RATS

Yagoub Hamadt Allah Elhaj*, Sanousi Soliman Mohammed, Zakia Abdelsamad Osman

ABSTRACT

This study was done to evaluate the effect of killed Streptococcus mutans to use as a dental caries vaccine in albino rats. To isolate S. mutans saliva was collected from persons suffering from dental caries. All specimens were inoculated on mitis salivarius bacitracin agar, which is a selective medium for isolation of S. mutans. All biochemical tests required to identify S. mutans were done.To obtain the killed S. mutans cells, the organism was cultured on mitis salivarius agar at 370c for 72hours. Some colonies were then transferred to a test tube containing 5ml of BHI broth and incubated at 370c for 16 hours. Twenty five microliter transferred to another test tube containing 10 ml of BHI broth with 2% sucrose. These tubes were incubated at 370c for 22hours and then the bacterial cells were collected by centrifugation. The bacterial cells were washed by normal saline and killed with 10% formalin. Thirty albino rats were bred in a suitable place, specially prepared for this target. The age range of these rats was between 50-60 days and of almost similar weights. The rats were then divided into 5 groups; each group containing 6 rats. Four groups of these were vaccinated using previously prepared vaccine (killed S. mutans cells). Immunization has been achieved via oral route. Meanwhile the other group was left not immunized as a control group. Blood and saliva specimens were collected from all groups before immunization and also one week, 2 weeks, and three weeks after immunization. The blood samples were used for a complete blood count by using autohematolyzer (sysmex), whereby saliva specimens were used for S.mutans cells count and the measurement immunoglobulin-A level. This study has shown a significant increase in white blood cells’ count, which composes the front defense line in the immune system, accompanied by an increase in the immunoglobulin- A level. This increase has led to a substantial decrease in Streptococcus mutans cell count. This decrease appeared obviously in three weeks; the thing that proves that the use of killed Streptococcus mutans have a great role in protecting teeth against caries, which is mainly caused by Streptococcus mutans. It is noticeable, through this study, that there has been a stability in the several components of blood (as for instance the hemoglobin concentration, red blood cells count and the platelets count), which indicates that there are no adverse side effects from the employment of this vaccine. So, it is possible to state that the use of this vaccine can provide sufficient protection against dental cavity.

Keywords: Streptococcus mutans, immunoglobulin-A, dental caries, vaccine.