Arthropod Ectoparasites Have Potential to Bind SARS-CoV-2 via ACE

Abstract

Coronavirus-like organisms have been previously identified in Arthropod ectoparasites (such as ticks and unfed cat flea). Yet, the question regarding the possible role of these arthropods as SARS-CoV-2 passive/biological transmission vectors is still poorly explored. In this study, we performed in silico structural and binding energy calculations to assess the risks associated with possible ectoparasite transmission. We found sufficient similarity between ectoparasite ACE and human ACE2 protein sequences to build good quality 3D-models of the SARS-CoV-2 Spike:ACE complex to assess the impacts of ectoparasite mutations on complex stability. For several species (e.g., water flea, deer tick, body louse), our analyses showed no significant destabilisation of the SARS-CoV-2 Spike:ACE complex, suggesting these species would bind the viral Spike protein. Our structural analyses also provide structural rationale for interactions between the viral Spike and the ectoparasite ACE proteins. Although we do not have experimental evidence of infection in these ectoparasites, the predicted stability of the complex suggests this is possible, raising concerns of a possible role in passive transmission of the virus to their human hosts.

Challenges at the host-arthropod-coronavirus interface and COVID-19: a One Health approach

“…Altogether, these findings support a possible role for arthropods at the host-coronavirus interface with potential implications as low-susceptible non-mammalian hosts and biological and/or passive vectors for SARS-CoV-2, possibilities that need to be evaluated in future research [9,30,35,[65][66][67].…”

“…Cement is secreted by ticks as a complex protein polymerization substance with antimicrobial properties and a role in host attachment and ectoparasite feeding [40]. Recent experiments showed that mosquitoes are not competent vectors for SARS-CoV-2 [42,43], results that agree with a predicted lower SARS-CoV-2 S-protein: ACE complex stability in insects [9]. Based on these results, it is possible that SARS-CoV-2 may be acquired by arthropod ectoparasites through feeding on infected hosts and may persist not only in contaminated mouthparts or exoskeleton [30], but also inside the vector through interactions with ACE and integrins for transmission to susceptible hosts by blood-meal regurgitation during secondary feeding or after transstadial transmission or inherited virus RNA [9,35,44,45].…”

“…Coronaviruses have been previously identified in ticks Ixodes uriae [34] and in unfed cat flea Ctenocephalides felis [35]. The application of experimentally validated models for SARS-CoV-2 S-ACE host receptor interactions support that not only vertebrate hosts, but also arthropod ACE may have the capacity to interact with SARS-CoV-2 S-protein [8,9,36]. Additionally, SARS-CoV-2 co-receptor integrins [37,38] have been described in tick salivary glands and cement [39,40] and in cat flea exoproteome [35,41].…”

“…Arthropods such as mosquitoes, flies, mites, fleas, lice and ticks can act as vectors of viruses and other pathogens via active biological transmission but also through passive mechanical transmission [9,[13][14][15][16] (Table 1, Ref. [17][18][19][20][21][22][23][24][25][26][27][28][29][30]).…”

“…Other animal species susceptible to SARS-CoV-2 but with low S-ACE interaction capacity (e.g., cats or pigs) would be susceptible to reverse zoonotic virus transmission with low risk for human infection [8]. Additionally, modelling interactions between SARS-CoV-2 S-protein and arthropod ACE receptor suggested a possible role for vectors in coronavirus transmission even if low viremia reduces the risk for transmission [9].…”