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Goals and Objective: Goal 1
Objective 1.2

Obj 1.2: Characterize epidemiology and pathogenesis of Israeli Acute Paralysis Virus (IAPV)) and develop RNA interference (RNAi) therapeutics for the treatment of the viral diseases

(Chen, Evans, Solter)

Rationale and significance
Among pathogens attacking honey bees, viruses are probably the least understood because of the lack of information about the dynamics underlying viral disease outbreaks. Gaining knowledge of the epidemiology and pathogenesis of viruses is an integral part of the study of viral disease outbreaks. IAPV was identified to be strongly associated with CCD and considered to be a significant marker for CCD (Cox-Foster et al., 2007). Therefore, this virus is a high-priority pathogen and can serve as a model for studying the epidemiology of virus transmission and the mechanisms of pathogenesis of viral diseases in honey bees. 

A crucial stage in the dynamics of virus infections is the mode of virus transmission. Knowing the transmission processes of diseases can enhance our understanding of the epidemiological potential of the viruses. Previous studies have shown that transmission of honey bee viruses could be horizontal and/or vertical (Chen and Siede, 2007). Although the transmission of several honey bee viruses has been elucidated previously and the parasitic mite Varroa destructor has been proven to be an effective vector for horizontal transmission of several honey bee viruses including Deformed Wing Virus (DWV) and Kashmir Bee Virus (KBV) (Bowen-Walker et al. 1999, Chen et al. 2004, Shen et al. 2005), knowledge concerning IAPV transmission pathways among honey bees is still lacking. It is not known whether Varroa mites also play a role in the transmission of IAPV. The investigation of the mode of transmission of IAPV can help gain insight into the epidemiological pattern of this virus and in turn lead to the development of effective strategies to block the spread and growth of the viruses in honey bees.   

Elucidating pathogenesis of viruses requires investigation of biological features of the viruses and their respective hosts. The outcome of a virus infection can vary from disease resistance or asymptomatic status to severe disease and depends on complex interactions between pathogen and host factors that control virus replication and disease pathogenesis. By comparing genome-wide gene expression in virus-challenged and virus-unchallenged bees, immune genes regulated by pathways linked to innate antiviral immunity can be identified and the host genetic markers can be selected for measurement of host defense responses. By evaluating the levels of virus titer and host immune responses in bees with different physiological and nutritional background, the impact of host status on the invasion of a virus and the subsequent development of disease can be evaluated. This study has great potential for giving insights into the mechanisms of host-virus interaction and honey bees’ anti-viral defense systems. A better understanding how the host responds to invasion by the virus and how the virus uses strategies to subvert host immune response should aid in finding therapeutic targets and developing methods for preventing and treating viral diseases.  

RNAi has rapidly emerged as a genetic tool for effectively combating infections by a variety of viruses. RNAi mediates sequence specific degradation of RNA and is triggered by double-stranded RNA. Positive-stranded RNA viruses are particularly vulnerable to RNAi because these viruses replicate through complementary genome strands, resulting in dsRNA replication intermediates that are attractive targets for siRNAs. Since the genomes of most honey bee viruses are positive-stranded RNA molecules, RNAi would be expected to be an important defense mechanism against viruses in bees. Further, a highly structured RNA sequence located in the 5′ untranslated region (5' UTR) and intergenic region (IGR) of IAPV genomes, called the internal ribosome entry site (IRES), is required for both protein translation and virus replication. Therefore, siRNA target sequences of IRES regions should offer promise for siRNA-based antiviral defense in honey bees.   

Nosema disease in European honey bees caused by N. ceranae is far more common and prevalent than that caused by N. apis (Reviewed in Fries, 2009). N. cerenae is known to cause chronic effects in honey bees including digestive disorder, reduced longevity, and decreased colony population size. Because of its debilitating nature, N. ceranae may weaken the bee immune response, physiology or midgut physical barriers to disease, making bees less resistant to virus proliferation and exacerbating disease effects. The investigation of how N. cerenae, N. apis and the viruses interact and how environmental conditions such as temperature influence the interaction of Nosema spp. and viruses will provide novel insights into the processes of the disease complex and lead to better strategies for controlling complex diseases. Additionally, these studies will provide information on the putative competitive advantage of N. ceranae over N. apis by comparing how each interacts with the viruses and abiotic stress. 

Expected outcomes

1) Identify transmission routes of IAPV infection in honey bees and define the role of Varroa mite in IAPV transmission and activation;

2) determine the spread and replication of IAPV infection under different host physiological and nutritional conditions;

3) identify genes that distinctly up-regulated in the virus-challenged bees to  develop host genetic markers for diseases and determine the novel host immune pathways in response to viruses,

4) Establish RNA silencing/interference (RNAi) as a mechanism of antiviral immunity against viruses in honey bees, and

5) characterize the effects of the possible synergistic interaction between N. ceranae and virus and N. apis and virus in disease progression.  

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Summary Statement for Goal 1
This goal constitutes our attempts at understanding the most important morbidity factors at work in North American Apis mellifera. Work in this Goal is characterized by a high degree of interinstitutional linkages within CAP labs, resulting in four topical groups. The Nosema group is comprised of Lee Solter (Univ IL), Tom Webster (KY State Univ), Zach Huang (MI State), Christina Grozinger (Penn State), and Kate Aronstein (ARS Weslaco). The virus group is made up of Jay Evans and Judy Chen (ARS Beltsville) and Lee Solter. There have been cross-group linkages with Greg Hunt (Purdue) who is studying the genetic basis of bee resistance to N. ceranae and Israeli Acute Paralysis Virus (IAPV). A diagnostics group is comprised of Jay Evans, Judy Chen, and Kate Aronstein. The toxicology group is comprised of Marion Ellis (Univ NB), Maryann Frazier, Jim Frazier, and Chris Mullin (Penn State). A sentinel apiary monitoring group, led by Frank Drummond (Univ. of Maine), is comprised of Nancy Ostiguy (Penn State), Marla Spivak (Univ. of Minn.), Kate Aronstein (ARS Weslaco), Sheppard (Univ. of Wash.), Kirk Visscher (Univ. of CA - Riverside); analytic work by Anne Averill (Univ. of Mass.), Nancy Ostiguy (Penn State), and Brian Eitzer (CT Experiment Station) is collecting baseline data on field colonies and factors contributing to bee morbidity. And finally, an IPM adoption group is headed up by Keith Delaplane (Univ GA).

Progress

Methodology, data and analysis of results to date are shared in an annual report to USDA. Papers generated by team members during the time of the CAP are listed and periodically updated below. Beyond the citation of published papers, the consensus of the group is that it would otherwise be unhelpful or possibly misleading to state preliminary results within the context on this web site.

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Publications of objective 1.2 principal investigators (Chen, Evans and Solter) to date during the CAP

Boncristiani, H., J.L. Li, J.D. Evans, and Y.P. Chen. 2011. Scientific note on PCR inhibitors in the compound eyes of honey bees, Apis mellifera, Apidologie (in press)

Chen, Y.P. and Z.Y. Huang. 2010. Nosema ceranae, a newly identified pathogen of Apis mellifera in the U.S. and Asia. Apidologie 41: 364-374, DOI: 10.1051/apido/2010021

Chen, Y.P., J.D. Evans, and J.S. Pettis. 2011. The presence of chronic bee paralysis virus
infection in honey bees (Apis mellifera L.) in the USA. J. Apic. Res.,50:85-86

Cornman, R. S., M.C. Schatz, J.S. Johnston, Y.P. Chen, J.S. Pettis, G. Hunt; B. Lanie, C. Elsik, D. Anderson, C.M. Grozinger, and J.D. Evans. 2010. Genomic survey of the ectoparasitic mite Varroa destructor, a major pest of the honey bee Apis mellifera, BMC Genomics 11:602

Dainat, B.D., J.D. Evans, Y.P. Chen, P. Neumann. 2011. Sampling and RNA quality for 
diagnosis of honey bee viruses using quantitative PCR, Journal of Virological 
Methods, (in press)

Di Prisco, G., F. Pennacchio, C. Emilio, H. Boncristiani, J.D. Evans, Y.P. Chen. 2011. Varroa destructor is an effective vector of Israeli Acute Paralysis Virus in honey bees, Apis mellifera, J. General Virology, 92: 151-155

Evans, J.D. 2006. Beepath: An ordered quantitative-PCR array for exploring honey bee immunity and disease, Journal of Invertebrate Pathology, 93 (2): 135-139

Evans, J.D., M. Spivak. 2010. Socialized Medicine: Individual and communal disease 
barriers in honey bees, Journal Invert. Pathol. 103, S62-S72

Genersch, E, J.D. Evans, I. Fries. 2010. Honey bee disease overview, Journal Invert. 
Pathol. 103, S2-S4

Johnson, R.M., J.D. Evans, G.E. Robinson, M.R. Berenbaum. 2009. Changes in transcript abundance relating to colony collapse disorder in honey bees (Apis mellifera). Proceedings of the National Academy of Sciences of the United States of America 106:14790-14795

Li, J.L., W.J. Peng, J. Wu,  H. Boncristiani, J.P. Strange, and Y.P. Chen. 2011. Cross-species Infection of Deformed Wing Virus Poses a New Threat to Pollinator Conservation.  J. Econ. Entomol.  104(3): 732-739

Paldi, N., E. Glick, M. Oliva, Y. Zilberberg, L. Aubin, J.S. Pettis, Y.P. Chen, J.D. Evans. 2010. Effective gene silencing of a microsporidian parasite associated with honey bee (Apis mellifera) colony declines, Applied Environmental Microbiology, 76:5960-5964

Peng, W.J., J.L. Li, J. Wu, H. Boncristiani, J.P. Strange, and Y.P. Chen. 2011. Host Range Expansion of Honey Bee Black Queen Cell Virus in the Bumble Bee, Bombus huntii. Apidologie (in press).

Solter, L.F. 2011. Microsporidia: Friend, Foe (And Intriguing Creatures). American Bee
Journal 150: 1147-1149

vanEngelsdorp D, J.D. Evans, C. Saegerman, et al. 2009. Colony collapse disorder: a
descriptive study. PLoS ONE 4 (8)

vanEngelsdorp,  D., N. Speybroeck, J.D. Evans, B.K. Nguyen, C. Mullin, M. Frazier, J. Frazier, D. Cox-Foster, Y.P. Chen, D.R. Tarpy, E. Haubruge, J.S. Pettis, C. Saegerman. 2010.  Identification of risk factors associated with bee Colony Collapse Disorder by classification and regression tree analysis. J. Econ Entomol, 103: 1517-1523

Zhang, X., S.Y. He, D.J. Evans, S.J. Pettis, G.F. Yin, and Y.P. Chen. 2011. New Evidence that Deformed Wing Virus and Black Queen Cell Virus are Multi-host Pathogens. J. Invertebr. Pathol.  (Submitted)

Further Background Information
Documentation of CAP progress in general, and of this objective in particular, is available through the following sources:

  1. Bee Health, an eXention initiative for peer-reviewed scientific recommendations
  2. Colony Collapse Disorder Progress Report for 2009
  3. Detect Nosema Parasite in Time to Save Bee Colonies
  4. Nosema ceranae – The Inside Story
  5. Microsporidia: Friend, Foe (and Intriguing Creatures)
  6. Genetic Toolkits for Bee Health

Updated July 22, 2011.

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