Utility of Insects for Studying Human Pathogens and Evaluating New Antimicrobial Agents

Abstract

Insect models, such as Galleria mellonella and Drosophila melanogaster have significant ethical, logistical, and economic advantages over mammalian models for the studies of infectious diseases. Using these models, various pathogenic microbes have been studied and many novel virulence genes have been identified. Notably, because insects are susceptible to a wide variety of human pathogens and have immune responses similar to those of mammals, they offer the opportunity to understand innate immune responses against human pathogens better. It is important to note that insect pathosystems have also offered a simple strategy to evaluate the efficacy and toxicity of many antimicrobial agents. Overall, insect models provide a rapid, inexpensive, and reliable way as complementary hosts to conventional vertebrate animal models to study pathogenesis and antimicrobial agents.

In vivo Activity of Copper(II), Manganese(II), and Silver(I) 1,10-Phenanthroline Chelates Against Candida haemulonii Using the Galleria mellonella Model

“…Most importantly, the innate immune system of G. mellonella possess several similarities with humans such as the similar lectin-mediated phagocytic mechanisms between hemocytes and neutrophils, respectively, identical cell surface receptors such as 3-glucan, identical signaling cascades of immune deficiency (IMD), c-Jun N-terminal kinases (JNK) and the Janus kinase/signal transducers and activators of transcription (JAK-STAT) pathways as well as nuclear factor-kappa B (NFkB) and IkB kinase transcription factors modulation by the toll and IMD pathways in the larvae and by the toll-like receptors and tumor necrosis factor alpha (TNF-α) in mammals (Browne et al, 2013;Wu et al, 2016). Moreover, a strong correlation involving microbial virulence and toxicity of novel antimicrobials between the G. mellonella and mammalian models has been established (Chamilos et al, 2007;Wang et al, 2013;Kavanagh and Sheehan, 2018). Therefore, the G. mellonella model has been widely used to assess the virulence of microbial pathogens and it was optimized to increase susceptibility to bacterial and fungal infections for testing the in vivo activity of antimicrobial agents (Kavanagh and Sheehan, 2018), which directly influenced our choice for this model in the current study.…”

Immune functions of pattern recognition receptors in Lepidoptera

“…There are also certain vital reasons, as follows. (i) The virulence factors of human pathogenic microorganisms are similar between insects and mammals, and their virulence is equivalent (6). (ii) Pathogens infect insects and mammals via identical mechanisms, including adhesion, invasion, systemic transmission and evasion of the immune response (7).…”

“…(iv) Insects are easy to breed, convenient to manipulate and economical. For a long time, Drosophila has been the chief insect model in gene level research; as a mini-host, it is advantageous for use for forward and reverse genetics (6). However, it also has some shortcomings, such as the inability to be propagated at 37°C, a small size and hemolymph volume (7); in addition, a wealth of operating experience and special laboratory equipment are needed (e.g., microsyringes) (10).…”