Candidatus Xenohaliotis californiensis AND ITS HYPERPHAGE IN BLUE AND YELLOW ABALONE OF THE PENINSULA OF BAJA CALIFORNIA, MEXICO  

Candidatus Xenohaliotis californiensis (CXc) is a rickettsiales-like prokaryote that replicates in intracellular membrane bound vacuoles commonly found in the digestive epitheliums of Haliotis spp. from the western coast of North America. This parasite is considered by the International Organization for Animal Health (OIE) as of obligatory declaration due to its pathogenicity. Although the presence of this pathogen has been confirmed in all species of Mexican abalone, to date there is no information on its epizootiology. Furthermore, it was unknown if the bacterial phage hyperparasite found in black abalone (Haliotis cracherodii) and red abalone (Haliotis rufescens) in California was also present in CXc infected blue abalone (Haliotis fulgens) and yellow abalone (Haliotis corrugata) from the peninsula of Baja California.

With the objective of determining the distribution, prevalence and intensity of CXc and its phage; as well as to study interactions between host sex and parasitism in blue and yellow abalone, tissue samples were obtained throughout the 2012-2013 capture season from 7 localities in the fishery zone. Two distinct inclusions were observed, one corresponding to the characteristic description of vacuoles formed by CXc (Figure 1. A) and a variant inclusion infected by a bacterial hyperphage (Figure 1. B), which was corroborated by TEM. The prevalence of CXc considering both inclusions was 80% in blue abalone and 62% in yellow abalone; while the prevalence of the phage infected variant inclusion was 18% and 15% in blue and yellow abalone, respectively. Low infection intensities were found in 86% of blue abalone and 82% of yellow abalone; although higher infection intensities were generally observed in undifferentiated organisms. The intensity of the variant inclusion was low in all analyzed localities. PCR analysis, product sequence analysis and in situ hybridization confirmed the identity and the presences of the parasite in both inclusions. These results show that CXc is widely distributed in the main abalone capture area of the peninsula of Baja California and that it is well established in natural populations of blue and yellow abalone. This data constitutes the first record of a bacterial phage hyperparasite in blue and yellow abalone as well as its distribution in the peninsula of Baja California México.