Contents lists available at ScienceDirect Experimental Parasitology journal homepage: www.elsevier.com/locate/yexpr DNA vaccination using recombinant Schistosoma mansoni fatty acid binding protein (smFABP) gene Ibrahim Aly a , Gehan ELnain a,b , Rabab S. Hamad a,c , Mona Kilany d,e , Hamed A. Ghramh f,g,h , Aly Alshehri h , Saad M. Dajem h , Essam H. Ibrahim h,i,* a Parasitology Laboratory, Theodor Bilharz Research Institute, Imbaba, P.O. Box 30, Giza, Egypt b Natural Science, Mathan Science Program, University College, Abu Dhabi University, United Arab Emirates c Biological Science Department, King Faisal University, Saudi Arabia d Biology Department, Faculty of Sciences and Arts, King Khalid University, Dhahran Al Janoub, Saudi Arabia e Department of Microbiology, National Organization for Drug Control and Research (NODCAR), Cairo, Egypt f Research Center for Advanced Materials Science (RCAMS), King Khalid University, P.O. Box 9004, Abha 61413, Saudi Arabia g Unit of Bee Research and Honey Production, Faculty of Science, King Khalid University, P.O. Box 9004, Abha 61413, Saudi Arabia h Biology Department, Faculty of Science, King Khalid University, P.O. Box 9004, Abha 61413, Saudi Arabia i Blood Products Quality Control and Research Department, National Organization for Research and Control of Biologicals, Cairo, Egypt ARTICLE INFO Keywords: DNA vaccination Schistosoma mansoni smFABP Schistosomiasis control Cloning ABSTRACT Schistosomiasis is a fatal disease that has a negative impact on health and economics. Praziquantel (PZQ) is the drug of choice for schistosomiasis treatment, but it has no prophylactic effect; therefore, vaccination is an es- sential requirement in schistosomiasis control. This work was carried out to investigate the possible effect of DNA vaccination against Schistosoma mansoni infection using recombinant S. mansoni fatty acid binding protein (rsmFABP). The smFABP gene was cloned into the eukaryotic expression vector pcDNAI/Amp in order to obtain an smFABP-pcDNAI recombinant plasmid (DNA vaccine) and was used for the intramuscular DNA vaccination of out-bread Swiss albino mice prior to infection with S. mansoni cercariae. Infected groups, either DNA vaccinated or unvaccinated, were treated with PZQ at week 6 post-infection. After 8 weeks post-infection, all mouse groups were sacrificed and parasitological, immunological and histopathological parameters were studied. DNA vac- cinated mice showed a high titer of anti-smFABP-IgG antibodies and acquired significant protection (74.2%, p < 0.01) against S. mansoni infection, with a reduction in ova and granuloma counts. DNA vaccinated and PZQ treated animals had higher titers of anti-smFABP-IgG antibodies and decreased (87%, P < 0.001) parenchymal granulomas compared to the DNA vaccinated PZQ untreated group. Infected mice, either non DNA vaccinated or vaccinated, had very high collagen content and fibrous granulomas (74%) compared to the PZQ treated group (10.3% fibrous granuloma) and PZQ treated + DNA vaccinated group (0% fibrous granuloma). In conclusion, DNA vaccination had protective and anti-pathological effects in naive mice and greatly improved the patholo- gical status in PZQ-treated animals, suggesting an immunological and pathological modulating effect of PZQ treatment. 1. Introduction Schistosomiasis, an acute and persistent parasitic disease, is the result of infection with blood trematode worms belonging to the genus Schistosoma. Reports estimated that at least 218 million people needed preventive treatment in 2015. To prevent or reduce morbidity, a pre- ventive remedy must be repeated many times for many years. Seventy- eight countries reported endemic schistosomiasis transmission, but preventive pharmacotherapy against schistosomiasis on a large-scale was carried out in only 52 nations (WHO, 2017). In Egypt, schistoso- miasis is one of the major public health problems (El-Khoby et al., 2000; Tendler et al., 2015; Dawaki et al., 2016). About 5–6 million schisto- somiasis cases were estimated to have occurred in 1990 (Barakat, 2013). The number of cases increased to 7 million in 2006 (Steinmann et al., 2006) and reached 7.2 million by 2012 (Hotez et al., 2012). Schistosoma mansoni and haematobium are present in Saudi Arabia. A study at the genotype level using random amplified polymorphic DNA (RAPD) for isolates of S. mansoni from Egypt, Saudi Arabia and Puerto https://doi.org/10.1016/j.exppara.2018.09.018 Received 28 November 2017; Received in revised form 23 July 2018; Accepted 23 September 2018 * Corresponding author. Department of Biology, Faculty of Science, King Khalid University, P.O. Box 9004, Abha, 61413, Saudi Arabia. E-mail address: essamebrahim@hotmail.com (E.H. Ibrahim). Experimental Parasitology 194 (2018) 53–59 Available online 25 September 2018 0014-4894/ © 2018 Elsevier Inc. All rights reserved. T