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Published on: August 26, 2020
Juvenile hormone enhances viral activity in bumble bees
Assaf Tzdaka1, Elad Bonda2, Adam G Dolezal3
1Department of Entomology, Agricultural Research Organization, The Volcani Institute, Rishon LeZion, Israel; The Robert H. Smith Faculty of Agriculture, Food and Environment, The Hebrew University in Jerusalem, Rehovot, Israel.
Juvenile hormone (JH) significantly increases Israeli acute paralysis virus (IAPV) replication in bumble bees, particularly in the fat body and ovaries. This hormonal effect on bee viruses highlights a critical link between host physiology and viral pathogenesis.
Area of Science:
- Insect Pathology
- Endocrinology
- Virology
Background:
- Bees face significant threats from viral infections, impacting both individual health and colony survival.
- Viruses rely on host cellular resources for replication, making host factors crucial for viral activity.
- Juvenile hormone (JH) is a key insect regulator influencing reproduction and metabolic rate.
Purpose of the Study:
- To investigate the influence of Juvenile hormone (JH) on viral replication in bees.
- To determine if elevated JH levels promote viral replication in a tissue-specific manner.
- To explore the relationship between JH, viral pathogenesis, and the bee immune system.
Main Methods:
- Utilized the bumble bee (Bombus terrestris) and Israeli acute paralysis virus (IAPV) model system.
- Compared IAPV replication in pre- and post-diapause queens with naturally low and high JH levels, respectively.
- Administered JH to pre-diapause queens before infection to establish causality and examined viral loads in various tissues.
- Measured the expression levels of key immune genes to assess immune system involvement.
Main Results:
- Post-diapause queens (high JH) exhibited significantly higher IAPV loads in the fat body and ovaries compared to pre-diapause queens (low JH).
- Exogenous JH application in pre-diapause queens led to substantially increased viral transcript levels in the fat body and ovaries.
- No additional increase in viral titers was observed when JH was supplemented in post-diapause queens, indicating a ceiling effect.
- No significant changes in the expression of major immune genes were detected, suggesting JH's effect is independent of immune modulation.
Conclusions:
- Juvenile hormone (JH) demonstrably enhances IAPV replication in specific bumble bee tissues, notably the fat body and ovaries.
- The observed enhancement of viral replication by JH is likely mediated by increased metabolic rate rather than immune system changes.
- This research reveals a crucial connection between insect hormones and viral disease progression, offering new insights into bee health and susceptibility to infections.
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