Prediction analysis of SARS-COV-2 entry in Livestock and Wild animals

SARS-CoV-2 is a viral pathogen causing life threatening disease in human. Interaction between spike protein of SARS-CoV-2 and ACE2 receptor on the cells is a potential factor in the infectivity of a host. Using in-silico analysis, the protein and nucleotide sequences of ACE2 were initially compared across different species to identify key differences among them. This phylogeny and alignment comparison did not lead to any meaningful conclusion on viral entry facilitation in different hosts. The 6LZG - Structure of novel coronavirus spike receptor-binding domain complexed with its receptor - ACE2, was taken as a reference, to model the ACE2 receptor of various species and assess its comparative binding ability to the spike receptor-binding domain of SARS-CoV-2. Out of the several parameters estimated concerning binding of ACE2 with spike receptor-binding domain, a significant difference between the known infected and uninfected species was observed for Entropy side chain, Van der Waals, Solvation Polar, Solvation Hydrophobic and Interface Residues. However, these parameters did not specifically categorize the animals into infected or uninfected, for all the Orders (of animals). This clearly established the fact that no single parameter should be used to predict SARS-CoV-2 entry. The logistic regression model constructed upon taking all the parameters led to inclusion of parameters - Interaction energy, entropy sidechain and entropy mainchain for estimating the probability of viral entry in different species. In the mammalian class, most of the species of Carnivores, Artiodactyls, Perissodactyls, Pholidota, and Primates showed high probability of viral entry. However, among the primates, baboons have very low probability of viral entry. Among rodents, hamster was highly probable for viral entry with rats and mice having a very low probability. Rabbits have a medium probability of viral entry. In Birds, ducks have a very low probability, while chickens seemed to have medium probability and turkey showed the highest probability of viral entry. Although, viral entry alone does not determine infection in host(s), the predictions emerged out of this study may prompt us to closely follow certain species of animals for determining pathogenic insult by SARS-CoV-2 and for determining their ability to act as a carrier and/or disseminator.