Research and IPM

Characterize the persistence and site of harborage of END virus in association with arthropod vectors.

Laboratory colonies of house fly (Musca domestica) and little house fly (Fannia canicularis) and litter beetle (Alphitobius diaperinus) were infected with END virus by forced contact with virus or choice feeding on a food/virus mixture (virus concentration similar to that found in manure from infected chicken). Insects were then held under constant laboratory conditions for up to seven days with a sub-sample of the potentially infected insects removed each day from day one to seven. Insects were either dissected to remove the gut from the remainder of the body or left intact; after which insects were pooled into groups of five insects, homogenized, and a 100 microliter aliquot was injected into embryonated chicken eggs. Flies were shown to harbor END virus for up to nine days (Fannia) or five days (Musca). Beetles were not successfully infected during these studies.

The majority of the virus was located in the gut of flies infected after choice feeding on a food/virus mixture suggesting that contamination of the external fly structures may be minimal in a field setting. Flies harbored enough virus for the first 24 to 48 hours to infect a chicken that might have consumed the fly.

Laboratory colonies of house fly, Musca domestica, little house fly, Fannia canicularis, and lesser mealworm beetle, Alphitobius diaperinus, have been established and maintained at UC Riverside for use in END persistence studies.

Standard Operating Procedures have been developed for handling infectious diseases at the USDA SERPL facilities. Handling and containment procedures were developed during a site visit by one of us (Gerry) conducted in January 2005 to discuss USDA requirements with our collaborators (Dr. David Swayne and Dr. Jack King, USDA SERPL). Required security clearances to work at this USDA laboratory facility have been granted for Gerry and postdoctoral researcher Dr. Seemanti Chakrabarti.

Dr. Chakrabarti is presently in Georgia, where studies on viral persistence in and on insects are currently under way at the USDA facility in Athens. Insects are being infected with END and held in isolation chambers within a quarantine facility on the grounds of the USDA research laboratory. Dr. Chakrabarti and the staff at the USDA facility have infected colony insects (house flies, little house flies, and darkling beetles), held these insects for up to 15 days post infection (p.i.) and are currently isolating virus from pools of these infected insects to determine how long virus can persist on our three representative insect species. This first infection trial will be completed for all three insect groups by May 11.

Thus far, we have found that infection of house flies and little house flies by providing a virus laden food source has been successful and that house flies were able to maintain detectable virus levels for a minimum of 72 hours. However, infection of beetles using a virus-laden substrate, while successfully accomplished previously using Newcastle Disease vaccine virus, provided spotty results with only some beetles apparently picking up virus during the 24-hour exposure period.

A second trial is scheduled for August 2006 to focus on additional questions that became evident following this first trial and to try new methods for infecting beetles.

Laboratory colonies of house fly (Musca domestica), little house fly (Fannia canicularis), and coastal fly (Fannia femoralis) have been established for use in END persistence studies that will begin in May and June 2005.

Standard Operating Procedures have been developed for handling infectious diseases at the USDA SERPL facilities. Handling and containment procedures were developed during a site visit by one of us (Gerry) in January 2005 to discuss USDA requirements with our collaborator (Dr. David Swayne, lab director at USDA SERPL). Required security clearances to work at this USDA laboratory facility have been applied for, and we are awaiting clearances to initiate the END persistence studies at the USDA facilities. The two researchers requiring security clearances to gain access to the USDA biosafety level 3 facilities that we will use (Gerry and postdoctoral researcher Dr. Seemanti Chakrabarti) expect to have clearances by June 2005.

Laboratory colonies of house flies (Musca domestica) and little house flies (Fannia canicularis) have been established for use in END persistence studies to be conducted in 2004 and 2005.