INDUCTION OF EXPRESSION OF PLASMODIUM FALCIPARUM PFS16, PFS230, PFS25, AND PFG27 GAMETOCYTE GENES FOLLOWING IN VITRO STIMULATION WITH ANTI-MALARIAL DRUGS ARTESUNATE, SULFADOXINE, PYRIRMETHMINE, QUININE, AND MOSQUITO SALIVARY GLANDS PRODUCTS
Authors: Zeinab Imam
Prof. Maowia M.Mukhtar, Dr. Muzamil Mahdi Abdel Hamid
Institute of Endemic Diseases, University of Khartoum, Sudan
Introduction: Malaria is a major health problem in sub-saharan Africa. Gametocytes are essential for Plasmodium transmission. Little is known about the initiation of gametocytogenesis in Plasmodium falciparum. This study aimed to detect the expression level of genes coding gametocyte-specific proteins Pfs16, Pfs230, Pfs25, and Pfg27 in P. falciparum parasite after stimulation with anti-malarial drugs (Artesunate, Sulfadoxine, Pyrirmethmine, and Quinine) and Anopheles mosquito salivary glands products at two different concentrations (High concentration IC50 and lower concentration 1:8 dilution).
Material and Methods: Laboratory based experimental study was conducted during the period 2013 to 2016. Two hundred malaria patients smear and ICT positive for falciparum were consented and recruited to the study mostly from Khartoum Teaching Hospital and Sherg Alneel Hospital. Thirty positive patients who had parasitemia ranged between 0.4- 0.6% were enrolled in the study. Blood samples were collected in Citrate Phosphate Dextrose Adenine (CPDA-1) tube. Real Time PCR was used to detect the expression level of the four target genes Pfs16, Pfs230, Pfs25, and Pfg27 and the house keeping gene A 18S rRNA in P. falciparum parasite after 72 hours in vitro culture stimulated with anti-malarial drugs and Anopheles mosquito salivary glands products.
Results: Anti-malarial drugs and Anopheles mosquito salivary glands products stimulated gametocytogenesis. The lower concentration of Artesunate, Sulfadoxine, and Quinine significantly stimulated the expression of the early gametocyte specific gene, Pfs16 (P = 0.004, P =0.006, P = 0.000, respectively). The IC50 of Pyrimethamine significantly stimulated the expression of Pfs16 gene with 23-fold increase and P = 0.004. Both IC50 of Pyrimethamine and Quinine (1:8 dilutions) had the highest stimulation level of Pfs16 compared with the other drugs. Interesting mosquito salivary glands products significantly stimulated the expression of Pfs16 gene at the higher concentration (>6-fold change and P = 0.045). The expression of Pfs16 mRNA was significantly stimulated by the anti-malarial drugs and mosquito salivary glands products (Artesunate P = 0.004, Sulfadoxine P = 0.006, Pyrirmethmine P = 0.004, Quinine P = 0.000, and mosquito salivary glands products P = 0.045) compared to the other genes. The transcript level of the gene Pfs25 showed a significant expression in low concentration of Artesunate (1:8 dilutions) P =0.033, IC50 of Pyrirmethmine (P = 0.039) and Quinine (1:8 dilutions). while Pfs230 transcript didn’t show a significant expression level in all anti-malarial drugs Sulfadoxine, Pyrirmethmine, Quinine and Anopheles mosquito salivary glands products (P= 0.897, P = 0.760, P = 0.357, P = 0.525, respectively).
Conclusions: This study documented the anti-malarial drugs (Artesunate, Sulfadoxine, Pyrirmethmine, and Quinine) induced gametocytogensis in P. falciparum. Anopheles mosquito salivary glands products induced gametocytogensis in P. falciparum. Pfs16 and Pfs25 were good early markers for detection of gametocytogenesis in P. falciparum.