Interactions Between Tsetse Endosymbionts and Glossina pallidipes Salivary Gland Hypertrophy Virus in Glossina Hosts

Abstract

Tsetse flies are the sole cyclic vector for trypanosomosis, the causative agent for human African trypanosomosis or sleeping sickness and African animal trypanosomosis or nagana. Tsetse population control is the most efficient strategy for animal trypanosomosis control. Among all tsetse control methods, the Sterile Insect Technique (SIT) is one of the most powerful control tactics to suppress or eradicate tsetse flies. However, one of the challenges for the implementation of SIT is the mass production of target species. Tsetse flies have a highly regulated and defined microbial fauna composed of three bacterial symbionts (Wigglesworthia, Sodalis and Wolbachia) and a pathogenic Glossina pallidipes Salivary Gland Hypertrophy Virus (GpSGHV) which causes reproduction alterations such as testicular degeneration and ovarian abnormalities with reduced fertility and fecundity. Interactions between symbionts and GpSGHV might affect the performance of the insect host. In the present study, we assessed the possible impact of GpSGHV on the prevalence of tsetse endosymbionts under laboratory conditions to decipher the bidirectional interactions on six Glossina laboratory species. The results indicate that tsetse symbiont densities increased over time in tsetse colonies with no clear impact of the GpSGHV infection on symbionts density. However, a positive correlation between the GpSGHV and Sodalis density was observed in Glossina fuscipes species. In contrast, a negative correlation between the GpSGHV density and symbionts density was observed in the other taxa. It is worth noting that the lowest Wigglesworthia density was observed in G. pallidipes, the species which suffers most from GpSGHV infection. In conclusion, the interactions between GpSGHV infection and tsetse symbiont infections seems complicated and affected by the host and the infection density of the GpSGHV and tsetse symbionts.

Interactions Between Glossina Pallidipes Salivary Gland Hypertrophy Virus and Tsetse Endosymbionts in Wild Tsetse Populations

“…The negative impact of Wolbachia infection on the GpSGHV infection in natural tsetse populations is in agreement with the recent report on the interaction of Wolbachia and GpSGHV infection in colonized tsetse populations [49]. However, it is important to note that the setting of this study have major differences from the design of the study of Demirbas-Uzel et al ( 2021).…”

“…The positive correlation between GpSGHV infection and Wigglesworthia infection observed in G. m. morsitans con icts with the negative correlation observed in the same species of colonized ies [49]. This result might re ect a speci c adaptation between a speci c strain of Wigglesworthia which reacts in a speci c way to increase its density in the presence of GpSGHV as a manner to restore and enhance the host immune system against the virus infection [75].…”

“…The results indicated that the interaction between the GpSGHV and tsetse symbionts is a complicated process that varied from one tsetse species to another. It is worth noting that the study of Demirbas-Uzel et al [49] was conducted in tsetse ies maintained under laboratory, controlled conditions (sustainable food availability, constant environmental conditions (temperature and humidity), and high density of the ies), which favors the increase of tsetse symbionts [45,50,[50][51][52]. In addition, this study was done using adults arti cially infected with GpSGHV by injection.…”

“…It was necessary, therefore, to investigate the infection status of the major tsetse endosymbionts (Wigglesworthia, Sodalis, and Wolbachia) in different tsetse species and their potential interaction. We have recently investigated the interaction between GpSGHV and tsetse symbionts in six tsetse species after virus injection under laboratory conditions [49]. The results indicated that the interaction between the GpSGHV and tsetse symbionts is a complicated process that varied from one tsetse species to another.…”

Microbiomes of Blood-Feeding Arthropods: Genes Coding for Essential Nutrients and Relation to Vector Fitness and Pathogenic Infections. A Review

“…infecting the reproductive organs. The nutritional benefits accorded to the tsetse fly host and the disruptive effects of Wolbachia on fly reproduction will be discussed elsewhere in this review [32].…”