Serological relationships of some viruses from cocoa (Theobroma cacao L.) in Ghana

Abstract

SUMMARY Strains A and Anibil of cocoa swollen‐shoot virus are serologically closely related. They are more distantly related to strain M and cocoa mottle‐leaf virus (Kpeve isolate), which are distantly related to one another. Strains A and Anibil protected against one another in cocoa seedlings, but no protection was found with any other combination between these four virus isolates. All mealybug‐transmitted cocoa viruses in West Africa are probably best considered as strains of cocoa swollen‐shoot virus.

Detection and Comparison of some Ghanaian Isolates of Cacao Swollen Shoot Virus (CSSV) by Enzyme‐Linked Immunosorbent Assay (ELISA) and Immunoelectron Microscopy (IEM) Using an Antiserum to CSSV Strain 1A

“…It can thus be concluded that the Kpeve and AD isolates differ considerably from the strain lA, although they react to a lower degree with the antiserum to strain IA. Our data support the results of LEGG and BONNEY (1967) and KENTEN and LEGG (1971), that the Kpeve and AD isolates be regarded as cacao mottle-leaf strains of cacao swollen shoot virus and not as a distinct virus.…”

“…Thus, Table 2C represents, on the one hand, isolates normally considered to be of the mottle-leaf type which are apparently mixed with 1 A-type particles, and on the other hand, an isolate (Mampong) normally considered to be of the typical swollen shoot type which is apparently mixed with mottle-leaf type particles. However, isolate Mampong is reported to be serologically only distantly related to strain lA (KENTEN and LEGG 1971). Our antiserum reacted strongly with most of the…”

“…particles of the Mampong samples (Table 2A and C). It remains unclear, therefore, whether our antiserum has a different heterologous reactivity from the antiserum used by KENTEN and LEGG (1971), or whether other factors may be responsible for the discrepancy. One sample each of Donkokrom and Onyimso-Agogo (Table 2B) showed virtually no decoration at an antiserum dilution of 1 :1600, did not show mottleleaf symptoms and were easily detected by ELISA and ISEM.…”

“…A comparison of our results with those published in the literature on serology, cross protection, host range, and vector specificity of CSSV isolates shows a general conformity. Serological studies on four isolates of CSSV in partially purified preparations by KENTEN and LEGG (1971) revealed that isolates 1A and Kpeve were serologically distantly related. The failure of cross protection between strain 1A and the Kpeve isolate (POSNETTE 1947, CROWDY andPOSNETTE 1947), and between strain lA and the AD isolates (originating from naturally infected Adansoma digitata, baobab) (ATTAFUAH and TINSLEY 1958), also indicates some differences of these isolates from strain lA.…”

“…However, the causal virus is very difficult to handle and until recently, no serological routine method for detecting the virus in cocoa plant sap was available. Although antisera to four isolates of CSSV were produced by KENTEN and LEGG (1971), the low virus concentration in infected plants prevented direct testing of crude extracts in gel double diffusion tests. Recently, antisera to severe strain 1A of CSSV have been produced which allowed the detection of this virus in crude extracts by ISEM (ADOMAKO etal.…”