Artificial in vitro infection of honey bee pupae with IAPV reveals viral interference with fundamental cell functions

The ongoing decline of honey bees in the USA, and in many other parts of the world, is raising serious concerns about the long-term availability of honey bee-assisted pollination of agricultural crops. A principle cause for the recent declines of honey bee populations may be the mysterious rapid loss of colony viability that has been called Colony Collapse Disorder (CCD). The causes for CCD are unclear but an association with the Israeli Acute Paralysis Virus (IAPV) has been reported. To better understand this pathogen, we developed an in vitro system for inoculation of honey bee pupae with IAPV. White-eye pupae infected with purified IAPV were followed over 48 hours under laboratory conditions. The pupae exhibited different patterns of disease. Symptoms varied from complete cessation of development with no visual evidence of disease to rapid darkening of parts or the whole body of the inoculated pupae. Real time PCR analysis showed incremental virus replication over time with no difference between different patrilines analyzed. However, individuals from the two colonies tested differ significantly with respect to the viral dynamics, suggesting genetic and/or environmental influences. Real time analysis of a small array of bee genes comprising immune, detoxification, developmental and housekeeping genes reveals significant up regulation of the majority of the transcript levels, including all housekeeping genes. The up regulation observed suggest that cells respond to IAPV interference with cellular translation, as has been reported from other Picornaviruses. We discuss the implications of these data for, IAPV pathogenesis, and real time PCR data analysis of virus-infected samples.