The attachment of SARA-CoV-2 happens between ACE2 and the receptor binding domain (RBD) on the spike protein. Mutations in this domain can affect the binding affinity of the spike protein for ACE2. S477N, one of the most common mutations reported in the recent variants, is located in the RBD.Today's computational approaches in biology, especially during the SARS-CoV-2 pandemic, assist researchers in predicting a protein's behavior in contact with other proteins in more detail. In this study, we investigated the interactions of the S477N-hACE2 in silico to find the impact of this mutation on its binding affinity for ACE2 and immunity responses using dynamics simulation, protein-protein docking, and immunoinformatics methods. Our computational analysis revealed an increased binding affinity of N477 for ACE2. Four new hydrogen and hydrophobic bonds in the mutant RBD-ACE2 were formed (with S19 and Q24 of ACE2), which do not exist in the wild type. Also, the protein spike structure in this mutation was associated with an increase in stabilization and a decrease in its fluctuations at the atomic level. N477 mutation can be considered as the cause of increased escape from the immune system through MHC-II.

Background:One of the most challenging isolates in nosocomial infections is Acinetobacter baumannii which is rapidly changing towards multi-drug resistant. Resistance to the last resort antibiotics, carbapenems, is reported around the world. In particular, metallo-β-lactamases (MBL) are responsible and detection of MBLs is of interest. Objectives: In this study we have evaluated the prevalence of MBLs in A. baumannii isolated during 2012 by two feasible described methods. Materials and Methods:In this cross sectional study, during 2012, 40 A. baumannii non-replicate isolates gathered from clinical and environmental specimens from Afzalipur hospital of Kerman. Isolates were characterized by conventional biochemical tests as A. baumannii-calcoaceticus complex (ABC). For antimicrobial susceptibility testing, 17 different antibiotics were sought by agar diffusion method. Phenotypic MBL detection was assessed by double disk test and Modified Hodge test for carbapenem resistant isolates. Results: During the study 40 isolates of ABC were collected. Of which, 23 (57%) isolates were resistant to carbapenems. Phenotypic MBLs detection was negative by two methods. Conclusions:The rates of resistance of the isolated ABCs in our clinical setting were at high level. Though, carbapenems were the most efficient antibiotic, but, there was a pronounced rate of resistant. MBL genes were not responsible for carbapenem resistance in under study clinical setting.