Pathogen Profiles

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Molecular Plant Pathology - Pathogen Profiles


Cowpea mosaic virus: effects on host cell processes

Jeroen Pouwels, Jan E. Carette, Jan Van Lent1 and Joan Wellink

Laboratory of Molecular Biology and Virology1, Graduate School for Experimental Plant Sciences, Wageningen University, Wageningen, the Netherlands


Taxonomy: Cowpea mosaic virus (CPMV) is the type member of the Comoviridae and bears a strong resemblance to animal picornaviruses, both in gene organization and in the amino acid sequence of replication proteins. Little systematic work has been done to compare isolates of the virus from different parts of the world.
Physical properties: Purified preparations of virus contain three centrifugal components; empty protein shells without RNA (T) and two nucleoprotein components (M and B), containing 24% and 34% RNA, respectively. The icosahedral particles have with a diameter of 28 nm, consist of 60 copies of two coat proteins, and are heat stable.
Hosts: CPMV causes one of the most commonly reported virus diseases of cowpea (Vigna unguiculata), in which it produces chlorotic spots with diffuse borders in inoculated primary leaves. Trifoliate leaves develop a bright yellow or light green mosaic of increasing severity in younger leaves. The host range is rather limited, and few hosts are known outside the Leguminosae. The virus is transmitted by various beetles with biting mouthparts. Reported in Africa, the Philippines and Iran. Is apparently absent from North and South America.
Useful websites: http://mmtsb.scripps.edu/viper/1cpmv.html (structure)
http://image.fs.uidaho.edu/vide/descr254.htm (general information)

Fig. 2 Electron micrographs of the cytopathological structure in CPMV infected cowpea leaves. (A) An osmium fixed thin section showing electron dense structures (Eds) and small membranous vesicles (Ve). Ch, chloroplast; Va, vacuole. (BD) Immunogold labelled cryo-sections of electron-dense structures (B and D) and vesicles (C and E) using anti-32K- (B and C), anti-VPg- (D and E) sera. With both antisera, gold particles were found associated with both structures. Bar represents 300 nm in (A) and 150 nm in (BE).

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