Honeybees use different sets of genes, regulated by two distinct mechanisms, to fight off viruses, bacteria and gut parasites, new research reveals.
The findings may help scientists develop honeybee treatments that are tailored to specific types of infections.
"Our results indicate that different sets of genes are used in immune responses to viruses versus other pathogens, and these anti-viral genes are regulated by two very distinct processes - expression and DNA methylation," said David Galbraith from the Pennsylvania State University.
The results appeared in the journal PLOS Pathogens.
According to Christina Grozinger, director of the Penn State Centre for Pollinator Research, beekeepers lose an average of 30 percent of their colonies every winter and an average of 25 percent in the summer.
"Honeybees have more than 20 types of viruses, and several of them have been linked to losses of honey bee colonies," she said.
Yet, beekeepers currently do not have any commercially available methods to reduce viral infections.
The researchers measured expression levels of all genes in the honeybee genome in both infected and uninfected bees.
They found that the RNAi pathway had increased activity and, therefore, is likely an important anti-viral immune pathway in bees.
"The RNAi pathway helps to cut up and destroy viral RNA so it is not infectious," Grozinger explained.
Scientists and beekeepers are increasingly interested in using RNAi approaches to control viruses and parasites in agricultural crops and in honeybee colonies, according to Grozinger.
The researchers also scanned the honeybee DNA for extra methylation marks that may have been added or removed from genes in virus-infected bees.
The team found that viral infections do change the pattern of DNA methylation in honeybees, and in a completely different set of genes from the ones in the RNAi pathway.
Many of these differentially methylated genes are also involved in anti-viral responses in mammals, said Grozinger.
