Gunasinghe, U.B. 1989 . Characterization of a new virus isolated from pineapple. University of Hawaii, Ph.D. Thesis 120 pp.

Notes: [Ph.D. Thesis; Thomas L. German, Advisor.] Mealybug-wilt of pineapple is one of the serious diseases in pineapple. Severe mealybug infestation may result in large yield losses in commercial plantations. The cause of this disease has been linked to a toxin secreted by mealybugs during their feeding upon pineapple. The biological evidence supporting a viral etiology began to emerge in recent years. In this study I investigated the possible involvement of a virus with this disease by studying the association of dsRNA with infected plants, developing purification protocols for the closterovirus-like particles associated with mealybug-wilt infected pineapple, conducting detailed electron microscopic studies of the virus leading to the determination of its physical properties such as length, width, and buoyant density. A polyclonal antiserum was produced to the virus isolated from pineapple and agar diffusion tests and serologically specific electron microscopic studies were conducted on this virus. The viral coat protein was analyzed by SDS-polyacrylamide gel electrophoresis. That the antiserum produced was specific to the viral coat protein was shown by western blotting studies. Complementary DNA (cDNA) probes were developed and were used for the detection of virus in pineapple plants, mealybugs, and other plant species found commonly near commercial pineapple plantations. cDNA probes also were used in Northern blot analysis to detect subgenomic RNAs of viral origin in plant extracts obtained from diseased pineapple plants. cDNA probes developed were sensitive and virus was detected in wilt-affected pineapple plants as well as symptomless pineapple plants in the commercial plantations. The presence of virus also was detected in mealybugs taken from diseased pineapple plants and in a common grass species around pineapple plantations. The results of this study confirm the presence of a virus associated with "mealybug-wilted" pineapple plants. Based on the virion morphology and its physical properties this virus may tentatively be assigned to the closterovirus group. The role of the virus in the etiology of wilt disease has yet to be determined.