Many have yet to give single-sense positive strand RNA viruses their proper place in infectious disease biology. I know I am not alone when I dedicated my life to the support of +SSRNA biology research decades ago and thank bees in their role in my Holiday meals. Most of the food and drink we have all consumed over these last few days depend on bee pollination. Over 100 foods including many fruits, nuts, and the beloved coffee plant require bees for pollination. Yet, bees are dying at record rates due to colony collapse as a result of RNA viruses even more destructive than the SARS-CoV-2 coronavirus. Dr. Sebastian Gisder and Dr. Elke Genersch have created a buzz this month with their imaging work furthering research on deformed winged viruses or DWVs and the ectoparasitic mite Varroa destructor that cause colony collapse in bees. Deformed winged viruses are like the SARS-CoV-2 virus (that causes COVID-19) in that they are single-sense positive strand RNA viruses.
This is the FIRST peer-reviewed publication using fluorescence-in situ-hybridization to provide compelling and direct evidence that the DWV-B variant infects the gut epithelium AND the salivary glands of V. destructor. Hence, these researchers have shown the host range of DWV includes both, bees (Insecta) and mites (Arachnida). These data contribute to a better understanding of the triangular relationship between honey bees, V. destructor and DWV and the evolution of virulence in this viral bee pathogen.
The full peer-reviewed article is available here.
Remember: We can’t live without bees! Do not buy neonicotinoid- grown or neonicotinoids-treated plants!
ABSTRACT
Deformed wing virus (DWV) is a bee pathogenic, single- and positive-stranded RNA virus that has been involved in severe honey bee colony losses worldwide. DWV, when transmitted horizontally or vertically from bee to bee, causes mainly covert infections not associated with any visible symptoms or damage. Overt infections occur after vectorial transmission of DWV to the developing bee pupae through the ectoparasitic mite Varroa destructor. Symptoms of overt infections are pupal death, bees emerging with deformed wings and shortened abdomens, or cognitive impairment due to brain infection. So far, three variants of DWV, DWV -A, DWV -B, and DWV -C, have been described. While it is 30 widely accepted that V. destructor acts as vector of DWV, the question of whether the mite only functions as a mechanical vector or whether DWV can infect the mite thus using it as a biological vector is hotly debated, because in the literature data can be found that support both hypotheses. In order to settle this scientific dispute, we analyzed putatively DWV -infected mites with a newly established protocol for fluorescence -in situ - hybridization of mites and demonstrated DWV -specific signals inside mite cells. We provide compelling and direct evidence that DWV -B infects the intestinal epithelium and the salivary glands of V. destructor. In contrast, no evidence for DWV -A infecting mite cells was found. Our data are key to understanding the pathobiology of DWV, the mite’s role as a biological DWV vector and the quasispecies dynamics of this RNA virus when switching between insect and arachnid host species.
IMPORTANCE
Deformed wing virus (DWV) is a bee pathogenic, originally rather benign, single- and positive -stranded RNA virus. Only the vectorial transmission of this virus to honey bees by the ectoparasitic mite Varroa destructor leads to fatal or symptomatic infections of individuals, usually followed by collapse of the entire colony. Studies on whether the mite only acts as a mechanical virus vector or whether DWV can infect the mite and thus use it as a biological vector have led to disparate results. In our study using fluorescence -in situ -hybridization we provide compelling and direct evidence that at least the DWV -B variant infects the gut epithelium and the salivary glands of V. destructor. Hence, the host range of DWV includes both, bees (Insecta) and mites (Arachnida). Our data contribute to a better understanding of the triangular relationship between honey bees, V. destructor and DWV and the evolution of virulence in this viral bee pathogen.