Research Product

Certain enveloped, rod-shaped DNA viruses have long been known as pathogens of insects under the descriptive term "nuclear polyhedrosis viruses." These viruses have been extensively and intensively studied since Berghold's early reports in 1947. Subsequent to Berghold's classic early studies, many rod-shaped viruses associated with polyhedral inclusion bodies of a crystalline nature have been described from different species of insects that represent several orders of Insecta. At present, The International Committee on Nomenclature of Viruses places the nuclear polyhedrosis viruses of arthropods in subgroup A under the genus or group name Baculovirus. Prior to 1973, there were no reports of viruses that resemble baculoviruses in animals other than insects or mites. In 1973 and 1974, the first reports were made of baculovirus-like particles and associated polyhedral inclusion bodies in a noninsect arthropod host. The new host was the pink shrimp, Penaeus duorarum, from Florida waters of the northern Gulf of Mexico. These reports indicated for the Baculovirus group a host range extension into the arthropod class Crustacea. In regard to specific characterization and identification of the shrimp virus, it is pertinent to report that not all of Koch's postulates have been satisfied. Koch's postulates, however, were meant to be used to show specificity of a microorganism as an etiologic agent for a disease condition and not specifically to determine phylogenetic affinity or identity of the microorganism. The latter task (identification) includes determination of biologic, morphologic, chemical and physical characteristics. Much of our effort has gone into these determinations for the shrimp virus. The first of Koch's postulates (that of association or presence of a microorganism with a disease condition) has been satisfied for patent virus infections in shrimp; that is, inclusion bodies and virions are present in all patent infections that exhibit cytopathologic characteristics. The second of Koch's postulates (that of isolation and pure culture of the microorganism) has not been satisfied for the shrimp virus and poses a severe problem because of the lack of continuous cell cultures of crustacean tissues in which to isolate and grow the virus. At present, we are attempting to use established insect cell lines in which to grow the shrimp virus. The baculoviruses have attracted much attention in recent years largely because some microbiologists and entomologists consider these viruses to be promising biologic control agents for numerous insect pests. The insect baculoviruses have shown narrow host specificity, and all experimental attempts so far to infect noninsect species with insect baculoviruses have failed. The purpose of the present paper is to consider the significance of the shrimp virus in regard to the ecology of its crustacean host.