SARS-CoV-2 variants show a gradual declining pathogenicity and pro-inflammatory cytokine stimulation and an increasing antigenic and anti-inflammatory cytokine induction

Hyper-transmissibility with decreased disease severity are typical characteristics of Omicron variant. To understand this phenomenon, we used various bioinformatics approaches to analyze randomly selected genome sequences (one each) of the Gamma, Delta, and Omicron variants submitted to NCBI from 15 to 31 December 2021. We show that: (i) Pathogenicity of SARS-CoV-2 variants decreases in the order: Wuhan > Gamma > Delta > Omicron; however, the antigenic property follows the order: Omicron > Gamma > Wuhan > Delta. (ii) Omicron Spike RBD has lower pathogenicity but higher antigenicity than other variants. (iii) Decreased disease severity by Omicron variant may be due to its decreased pro-inflammatory and IL-6 stimulation and increased IFN-{gamma} and IL-4 induction efficacy. (iv) Mutations in N protein are associated with decreased IL-6 induction and human DDX21-mediated increased IL-4 production in Omicron. (v) Due to mutations, the stability of S, M, N, and E proteins decreases in the order: Omicron > Gamma > Delta > Wuhan. (vi) Stronger Spike RBD-hACE2 binding in Omicron is associated with increased transmissibility. However, the lowest stability of the Omicron Spike protein makes Spike RBD-hACE2 interaction weak for systemic infection and for causing severe disease. Finally (vii), the highest instability of Omicron E protein may also be associated with decreased viral maturation and low viral load leading to less severe disease and faster recovery. Our method may be used for other similar viruses, and these findings will contribute to the understanding of the dynamics of SARS-CoV-2 variants and the management of emerging variants.

Meckel's Diverticulum Enterolith: A Rare Cause of Perforation and Small Bowel Obstruction Presenting as Acute Abdomen.

Meckel's diverticulum (MD) is the most common congenital anomaly of the gastrointestinal tract. MD enteroliths are an uncommon entity that could rarely present with complications. We, herein, present a case of a 56-year-old man who presented with severe abdominal pain. Preoperative CT showed an inflamed structure with central calcification connected to distal ileum lumen with an air pouch associated with small bowel obstruction. Upon laparotomy, a perforated MD was found with phlegmon formation. He underwent resection of the loops containing MD with end-to-end anastomosis.  This highlights the importance of radiological imaging in preoperative diagnosis of these conditions which should be kept in mind if we find a calcified lesion in an inflamed diverticulum around the midline region.