Comparison of in vitro-cultured and wild-type XXXX . II. Dosing methods and host response.

@entity23682 @entity26 @entity281 @entity4801 @entity42384
Endoparasites must breach host barriers to establish @entity281 and then must survive host internal defenses to cause disease. Such barriers may frustrate attempts to experimentally transmit @entity4801 by 'natural' methods. In addition, the host's condition may affect a study's outcome. The experiments reported here examined the effect of dosing method and host metabolic condition on measures of virulence for the oyster parasite @entity42384 . Oysters, @entity23682 , were challenged with wild-type and cultured forms of @entity42384 via feeding, shell-cavity injection, gut intubation and adductor-muscle injection. For both parasite types, adductor-muscle injections produced the @entity281 followed by shell-cavity injection, gut intubation, and feeding. There was no difference in parasite burdens between oysters fed cultured cells by acute vs chronic dosing, and parasite loads stabilized over time, suggesting a dynamic equilibrium between invasion and elimination. @entity42384 distribution among tissues of challenged oysters indicated that @entity4801 invaded the mantle and gill, as well as the gut, which has been considered the primary portal of entry. Frequency distributions of @entity42384 in oysters challenged with 3 different culture phases indicated an aggregated distribution among hosts and suggested that stationary-phase @entity4801 were easiest for the oyster to control or eliminate and log-phase @entity4801 were the most difficult. Host metabolic condition also affected experimental outcomes, as indicated by increased @entity281 levels in oysters undergoing spawning and/or exposed to low @entity26 stress.
