Arch Virol (2003) 148: 2449–2460 DOI 10.1007/s00705-003-0187-5 Some molecular characteristics of three viruses from SPVD-affected sweet potato plants in Egypt Brief Report J. A. IsHak 1,2,∗ , J. F. Kreuze 2,∗ , A. Johansson 2 , S. B. Mukasa 2,3 , F. Tairo 2,4 , F. M. Abo El-Abbas 1 , and J. P. T. Valkonen 2,5 1 Department of Plant Pathology, Faculty of Agriculture, Ain Shams University, Cairo, Egypt 2 Department of Plant Biology, Genetics Centre, Swedish University of Agricultural Sciences, Uppsala, Sweden 3 Department of Crop Science, Faculty of Agriculture, Makerere University, Kampala, Uganda 4 Mikocheni Agricultural Research Institute, Dar es Salaam, Tanzania 5 Department of Applied Biology, University of Helsinki, Helsinki, Finland Received March 19, 2003; accepted July 3, 2003 Published online September 16, 2003 c  Springer-Verlag 2003 Summary. Sweet potato feathery mottle virus (SPFMV, genus Potyvirus, family Potyviridae), Sweet potato chlorotic stunt virus (SPCSV, genus Crinivirus, family Closteroviridae) and sweet potato virus G (SPVG) were detected in naturally infected sweet potato plants grown in the Delta region in Egypt. Before this study, SPVG was reported only from China. Two isolates of SPFMV and one isolate of SPVG were characterized for the 3 ′ -proximal genomic sequences. Phylogenetic analyses indicated that the SPFMV isolates belong to the ‘russet crack’strain group (RC). Serological tests using monoclonal antibodies, and phylogenetic analysis of a partial sequence of the Hsp70 gene, indicated that the Egyptian SPCSV belongs to the so-called non-East African strain group of SPCSV. ∗ Sweet potato, Ipomoea batatas (L.) Lam., is the third most important root crop in the world after potato (Solanum tuberosum L.) and cassava (Manihot escu- lenta Crantz) [10]. Sweet potato originated in Central America or northern South America and is currently grown throughout the tropical and subtropical parts of ∗ The two first authors contributed equally to this work.