Identification and characterization of two novel C‐type lectins from the larvae of housefly, Musca domestica L.

Abstract

Lectins and antimicrobial peptides (AMPs) are widely distributed in various insects and play crucial roles in primary host defense against pathogenic microorganisms. Two AMPs (cecropin and attacin) have been identified and characterized in the larvae of housefly. In this study, two novel C-type lectins (CTLs) were obtained from Musca domestica, while their agglutinating and antiviral properties were evaluated. Real-time PCR analysis showed that the mRNA levels of four immune genes (MdCTL1, MdCTL2, Cecropin, and Attacin) from M. domestica were significantly upregulated after injection with killed Gram-negative Escherichia coli. Moreover, purified MdCTL1-2 proteins can agglutinate E. coli and Staphylococcus aureus in the presence of calcium ions, suggesting their immune function is Ca dependent. Sequence analysis indicated that typical WND and QPD motifs were found in the Ca -binding site 2 of carbohydrate recognition domain from MdCTL1-2, which was consistent with their agglutinating activities. Subsequently, antiviral experiments indicated that MdCTL1-2 proteins could significantly reduce the infection rate of Spodoptera frugiperda 9 cells by the baculovirus Autographa californica multicapsid nucleopolyhedrovirus, indicating they might play important roles in insect innate immunity against microbial pathogens. In addition, MdCTL1-2 proteins could effectively inhibit the replication of influenza H N virus, which was similar to the effect of ribavirin. These results suggested that two novel CTLs could be considered a promising drug candidate for the treatment of influenza. Moreover, it is believed that the discovery of the CTLs with antiviral effects in M. domestica will improve our understanding of the molecular mechanism of insect immune response against viruses.

Hepatopancreas-Specific Lectin Participates in the Antibacterial Immune Response by Regulating the Expression of Antibacterial Proteins

“…Further study showed that HepCL could regulate the expression of antimicrobial proteins (Figures 6, 7). Invertebrates lack an acquired immune system, and effector molecules such as antimicrobial peptides (AMPs) play important roles in innate immunity (53). The rapid synthesis and release of active AMPs is a significant strategy in invertebrate host defenses.…”

A C‐type lectin with a single carbohydrate‐recognition domain involved in the innate immune response of Tribolium castaneum

“…In addition to binding and agglutination activities, CTLs, as PRRs, also exhibit antimicrobial activity by regulating the expression of AMPs. AMPs are generally small cationic molecules that exhibit bioactivity against bacteria, fungi and viruses (Zhou et al , ). EsLecH (APA32005) can regulate AMPs via JNK signalling to restrain bacterial proliferation (Zhu et al , ) .…”

Bombyx mori C-Type Lectin (BmIML-2) Inhibits the Proliferation of B. mori Nucleopolyhedrovirus (BmNPV) through Involvement in Apoptosis

“…Aedes aegypti mosGCTL-1 collaborates with the human CD45 homolog mosPTP-1 to enable attachment and entry of the West Nile virus (WNV) [ 21 ]. In Musca domestica L, MdCTL1 and MdCTL2 could effectively reduce the infection of Sf 9 cells by Autographa californica multicapsid nucleopolyhedrovirus (AcMNPV) and dramatically inhibit the proliferation of influenza H1 N1 virus [ 22 ]. In short, the roles of insect C-type lectins in viral infection have been increasingly investigated and reported.…”