Insight into a Conserved Lifestyle: Protein-Carbohydrate Adhesion Strategies of Vector-Borne Pathogens

Abstract

The incidence of vector-borne diseases such as malaria, den- gue, African sleeping sickness, and tick-borne fevers is increas- ing. Given that current global control efforts have met with limited success, the need to develop novel interventions has become all the more vital. Successful discovery of such inter- ventions is contingent on improving our understanding of how the pathogen interacts with its vertebrate host and also with its invertebrate vector. In this review we examine a premise de- veloped more than 20 years ago (94) that emphasized the role of protein-carbohydrate interactions in microbial pathogene- sis, and we present it in the context of vector-pathogen dynam- ics. Glycans are "essential macromolecules for numerous cellu- lar processes, such as signaling, structural-support, cell-cell interaction, cell-matrix adhesion, growth, protection and traf- ficking" (94). Their ubiquitous yet tissue-specific occurrence as cell surface glycoconjugates has, over evolutionary time, been exploited by several pathogenic microorganisms as receptors for attachment and invasion (95). While evidence for microbial adherence to mammalian glycolipids and glycoproteins contin- ues to grow (for reviews see references 17, 18, 58, 95, and 115), only recently has evidence for a "protein-carbohydrate recog- nition strategy" for vector host-pathogen interactions emerged. This review focuses on the most recent advances that describe adherence mechanisms of three different classes of patho- gens—bacteria, viruses, and protozoan parasites—to their ob- ligate arthropod vectors. We also discuss how the protein- carbohydrate recognition strategies in both vector and mammalian life stages are apparently conserved and how this conservation could lead to the development of novel strategies for intervention.