The Effect of the Musca domestica Salivary Gland Hypertrophy Virus on Food Consumption in Its Adult Host, the Common House Fly (Diptera: Muscidae)

A deep insight into the sialome of the house fly, Musca domestica, infected with the salivary gland hypertrophy virus (MdSGHV)

The house fly, Musca domestica, serves as a mechanical vector for numerous pathogens, posing a significant risk to human and animal health. More than two decades ago, the Musca domestica salivary gland hypertrophy virus (MdSGHV) was discovered, infecting both males and females flies and disrupting mating and the reproductive process. While MdSGHV can infect various tissues, its primary replication site is the house fly salivary gland. It is well established that arthropod salivary glands play an important role not only in acquiring food but also in transmitting pathogens. Therefore, understanding the composition of vector salivary glands and the interactions between vector and pathogen components is essential for developing future control strategies. To this end, we conducted a comprehensive RNA-sequencing of salivary glands from both infected and non-infected house flies. Our analysis identified a total of 6,410 putative sequences, with 6,309 originating from M. domestica and 101 from the MdSGHV, categorized into 25 functional groups. Furthermore, differential expression analysis between infected and non-infected salivary glands revealed 2,852 significantly modulated transcripts, highlighting profound transcriptional changes triggered by MdSGHV infection. Overall, these findings not only deepen our understanding of the composition of M. domestica salivary glands but also provide valuable insight into the virus-vector interaction, which could serve as a model to understand other medically relevant interactions.

Quantification of saliva production in Musca domestica L. (Diptera: Muscidae) and the impact of MdSGHV infection

Musca domestica salivary gland hypertrophy virus (MdSGHV) affects house flies by enlarging salivary glands, impeding ovary development in females, and mating behavior in both males and females. It is not known if this virus impacts the quantity of saliva produced by house flies. This study aimed to establish baseline saliva quantities in healthy M. domestica across sexes and ages and examine how MdSGHV infection influences saliva output in 5-day-old males. Results reveal that healthy female Musca domestica produce more saliva on average than males and that saliva production among both sexes decreases with age. A comparison of infected, PBS-injected, and healthy flies shows significantly higher saliva quantities in infected individuals, suggesting MdSGHV enhances saliva production to improve transmission. These findings provide insights into MdSGHV transmission dynamics, which may provide for a better understanding of how other vector-borne diseases like Zika and Dengue virus interact in the infected salivary glands of the host vector.

A Systematic Review on Viruses in Mass-Reared Edible Insect Species

Edible insects are expected to become an important nutrient source for animals and humans in the Western world in the near future. Only a few studies on viruses in edible insects with potential for industrial rearing have been published and concern only some edible insect species. Viral pathogens that can infect insects could be non-pathogenic, or pathogenic to the insects themselves, or to humans and animals. The objective of this systematic review is to provide an overview of the viruses detected in edible insects currently considered for use in food and/or feed in the European Union or appropriate for mass rearing, and to collect information on clinical symptoms in insects and on the vector role of insects themselves. Many different virus species have been detected in edible insect species showing promise for mass production systems. These viruses could be a risk for mass insect rearing systems causing acute high mortality, a drastic decline in growth in juvenile stages and in the reproductive performance of adults. Furthermore, some viruses could pose a risk to human and animal health where insects are used for food and feed.