1. Department of Medical microbiology, Faculty of Medical Laboratory Science, El Neelain University, Khartoum, Sudan
2. Department of Virology, Central Laboratory- The Ministry of Higher Education and Scientific Research, P.O. Box 7099, Khartoum, Sudan
3. Department of Microbiology and Parasitology, Faculty of Medicine, University of Khartoum, Khartoum, Sudan