Prevalence of white spot syndrome virus (WSSV) in wild shrimp Penaeus monodon in the Philippines.

Prevalence of white spot syndrome virus (WSSV) was determined using polymerase chain reaction (PCR) methodology on DNA extracted from the gills of wild black tiger shrimp Penaeus monodon collected from 7 sampling sites in the Philippines. These 7 sampling sites are the primary sources of spawners and broodstock for hatchery use. During the dry season, WSSV was detected in shrimp from all sites except Bohol, but during the wet season it was not detected in any site except Palawan. None of the WSSV-PCR positive shrimp showed signs of white spots in the cuticle. Prevalence of WSSV showed seasonal variations, i.e. prevalence in dry season (April to May) was higher than in the wet season (August to October). These results suggest that WSSV has already become established in the local marine environment and in wild populations of P. monodon. Thus, broodstock collected during the dry season could serve as the main source of WSSV contamination in shrimp farms due to vertical transmission of the virus in hatcheries.

Training needs and provision in developing countries of the Asia-Pacific region.

Training has played a significant role in the development of capacity in aquatic animal health in the Asia-Pacific region where most specialists have fisheries or a background in biology rather than in veterinary medicine. Training courses offered by various organizations, national institutes, universities and the private sector are aimed at providing graduates with skills in disease diagnostics using molecular methods, histopathology, epidemiology, immunology, as well as in disease prevention and control methods. Most training programmes either focus on diseases affecting specific commodities, such as shrimp, marine fish or molluscs, or on diagnostic methods for pathogens such as viruses. Because of the need to train a large pool of geographically dispersed participants, innovative and cost-effective ways of delivery like online and on-site training should be encouraged as well as workshops preceding or following meetings and symposia. One important aspect to be addressed is the translation of training materials to facilitate knowledge transfer to the farm level. Since the inadequate level of aquatic animal health expertise in the Asia-Pacific affects worldwide aquaculture, partnerships between governments, various international organizations and academia should be strengthened in order to fill the training gap.

Genomic polymorphism in symbiotic populations of Photobacterium leiognathi.

Photobacterium leiognathi forms a bioluminescent symbiosis with leiognathid fishes, colonizing the internal light organ of the fish and providing its host with light used in bioluminescence displays. Strains symbiotic with different species of the fish exhibit substantial phenotypic differences in symbiosis and in culture, including differences in 2-D PAGE protein patterns and profiles of indigenous plasmids. To determine if such differences might reflect a genetically based symbiont-strain/host-species specificity, we profiled the genomes of P. leiognathi strains from leiognathid fishes using PFGE. Individual strains from 10 species of leiognathid fishes exhibited substantial genomic polymorphism, with no obvious similarity among strains; these strains were nonetheless identified as P. leiognathi by 16S rDNA sequence analysis. Profiling of multiple strains from individual host specimens revealed an oligoclonal structure to the symbiont populations; typically one or two genomotypes dominated each population. However, analysis of multiple strains from multiple specimens of the same host species, to determine if the same strain types consistently colonize a host species, demonstrated substantial heterogeneity, with the same genomotype only rarely observed among the symbiont populations of different specimens of the same host species. Colonization of the leiognathid light organ to initiate the symbiosis therefore is likely to be oliogoclonal, and specificity of the P. leiognathi/leiognathid fish symbiosis apparently is maintained at the bacterial species level rather than at the level of individual, genomotypically defined strain types.