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Etiology

Use of Polyclonal Antisera and Monoclonal Antibodies to Examine Serological Relationships Among Three Filamentous Viruses of Sweetpotato. John Hammond, U.S. Department of Agriculture, Agricultural Research Service, Florist and Nursery Crops Laboratory, Beltsville Agricultural Research Center, Beltsville, MD 20705-2350; Ramon L. Jordan(2), Richard C. Larsen(3), and James W. Moyer(4). (2)U.S. Department of Agriculture, Agricultural Research Service, Florist and Nursery Crops Laboratory, Beltsville Agricultural Research Center, Beltsville, MD 20705-2350; (3)(4)Department of Plant Pathology, North Carolina State University, Raleigh 27695-7616; (3)Present address: U.S. Department of Agriculture, Agricultural Research Service, Prosser, WA 99350-9687. Phytopathology 82:713-717. Accepted for publication 3 March 1992. This article is in the public domain and not copyrightable. It may be freely reprinted with customary crediting of the source. The American Phytopathological Society, 1992. DOI: 10.1094/Phyto-82-713.

Sweetpotato is susceptible to infection by several filamentous viruses of which only the aphid-transmitted sweetpotato feathery mottle virus (SPFMV) has been well-characterized. Sweetpotato mild mottle (SPMMV; transmitted by whiteflies) and sweetpotato latent (SPLV; for which no vector has been identified) viruses, although well-recognized, have not been definitively classified. The serological relationships among these viruses were re-examined with SPFMV-, SPLV- and SPMMV-specific polyclonal antisera and potyvirus cross-reactive monoclonal antibodies (MAbs). No significant relationships were detected between SPMMV and SPFMV, SPLV, or any other aphid-transmitted potyvirus. None of the MAbs reacted to SPMMV. Several MAbs reacted with epitopes common to SPFMV and SPLV, whereas others reacted with epitopes on only one of these viruses. With the exception of one MAb specific for SPFMV, all MAbs used recognized epitopes present on other distinct potyviruses. An apparent distant relationship between SPFMV and SPLV was also revealed by probing Western blots with respective polyclonal antiserum. Thus, SPFMV and SPLV share some common epitopes but are easily differentiated when potyvirus cross-reactive MAbs are used. SPMMV appears to be serologically distinct from any of the aphid-transmitted potyviruses; it possesses none of the epitopes recognized by the MAbs used. These MAbs included PTY 1, which cross-reacts with almost every aphid-transmitted potyvirus (and SPLV) so far tested. We concluded that SPFMV, SPLV, and SPMMV are three separate but atypical potyviruses, and SPFMV and SPLV are more closely related to typical aphid-transmitted members of the potyvirus group.