Cluster analysis on algicidal activity of HaV clones and virus sensitivity of Heterosigma akashiwo (Raphidophyceae)

After analyzing the algicidal activity spectra of 13 HaV (Heterosigma akashiwo virus) clones against 33 H. akashiwo strains by means of the unweighted pair-group method analysis (UPGMA) and neighbor-joining (NJ) method, they were tentatively classified into three clusters. On the basis of the analysis, however, HaV clones did not show any clear correlation with their isolation locality or sample source, i.e, from water or sediment, except for the case of HaV15 which was newly isolated from Nomi Bay in 1997. In contrast, as for cluster analysis of the infection specificity of 33 H. akashiwo strains against 13 HaV clones, they were classified into four tentative clusters, although we could not obtain a statistically meaningful result. These results suggest the high diversity in both HaV and its host H. akashiwo in regard to virus infection in the natural host-virus system. The present data provide a background for further studies on mechanisms of infection specificity of HaV.