aAfro-Egypt J Infect  Endem  Dis  2016 September ; 6(3):142

A molecular Approach for Evaluation of Experimental Trials of Anti Schistosomal Vaccination in Murine Models

Samia E. Etewa¹, Mohamed H. Abdel Hady¹, Ashraf S. Metwally¹,Somia H. Abd Allah², Sally M. Shalaby², Amal S. El-Shal²,Mahmoud A. El Shafey³, Howayda S.F.Moawad¹                                     Medical Parasitology¹, Biochemistry² and Clinical Pathology³ Departments, Faculty of Medicine                                     Zagazig University, Zagazig, Egypt.

drsamiaetewa@hotmail.com

 

ABSTRACT

Background and study aim: Current  schistosomiasis control strategies are  mainly  based  on  chemotherapy,  but  many  researchers  believed  that  the  best  long term  strategy  to  control  schistosomiasis  is  through immunization with  anti-schistosomiasis vaccines. This study aims at assessment of the efficacy of different potential anti-schistosomal vaccines (as crude soluble egg antigens (SEA), soluble worm antigen preparation (SWAP) and combined SEA & SWAP) by parasitological and molecular studies in experimental murine models.  

Materials and Methods: Sixty male laboratory bred Swiss Albino mice were used  and divided into six groups; control normal (G1), control infected by ± 80  cercariae by S.C. route (G2), Freund’s adjuvant (adj.) received then infected (G3), SEA+adj. received then infected (G4), SWAP+ adj. received then infected (G5) and combined (SEA+SWAP) + adj. received then infected (G6). A schedule of sensitization, immunization and schistosomiasis challenge were followed and performed on different mice groups. Mice were euthanized 10 weeks post-infection. Potential vaccine efficacy was investigated by parasitological and molecular studies including egg count/gram stool using modified Kato thick smear, liver egg load, oogram pattern in the liver and stool PCR to detect S. mansoni egg DNA in stools of studied mice. 

Results: The combined (SEA+SWAP) vaccine caused the highest significant reduction in the fecal egg count followed by SWAP then SEA antigens. On the other hand, the highest percentage reduction in eggs/gram liver tissue was attributed to the combined (SEA+SWAP) followed by SEA then SWAP antigens. Regarding oogram results, the combined (SEA+ SWAP) antigens were more efficient in increasing the number of dead ova with highly significant reduction in the number of mature & immature ova, followed by SEA then SWAP antigens. The lowest percentage of S. mansoni egg DNA detected by PCR in stool samples was encountered with the combined (SEA+ SWAP), followed by SEA then SWAP antigens.

Conclusion:The parasitological and PCR-based assessment studies denoted that the combined (SEA+SWAP) vaccine candidate was the most effective in protection against schistosomiasis challenge. The results of parasitological and molecular studies were nearly similar but the molecular study was more sensitive, definite and accurate.