Robust memory humoral immune response to SARS-CoV-2 in the tonsils of adults and children.

Background: Adaptive humoral immunity against SARS-CoV-2 has mainly been evaluated in peripheral blood. Human secondary lymphoid tissues (such as tonsils) contain large numbers of plasma cells that secrete immunoglobulins at mucosal sites. Yet, the role of mucosal memory immunity induced by vaccines or natural infection against SARS-CoV-2 and its variants is not fully understood. Methods: Tonsillar mononuclear cells (TMNCs) from adults (n=10) and children (n=11) were isolated and stimulated using positive SARS-CoV-2 nasal swabs. We used endpoint enzyme-linked immunosorbent assays (ELISAs) for the measurement of anti-S1, -RBD, and -N IgG antibody levels and a pseudovirus microneutralization assay to assess neutralizing antibodies (nAbs) in paired serum and supernatants from stimulated TMNCs. Results: Strong systemic humoral response in previously SARS-CoV-2 infected and vaccinated adults and children was observed in accordance with the reported history of the participants. Interestingly, we found a significant increase in anti-RBD IgG (305 and 834 folds) and anti-S1 IgG (475 and 443 folds) in the stimulated TMNCs from adults and children, respectively, compared to unstimulated cells. Consistently, the stimulated TMNCs secreted higher levels of nAbs against the ancestral Wuhan strain and the Omicron BA.1 variant compared to unstimulated cells by several folds. This increase was seen in all participants including children with no known history of infection, suggesting that these participants might have been previously exposed to SARS-CoV-2 and that not all asymptomatic cases necessarily could be detected by serum antibodies. Furthermore, nAb levels against both strains were significantly correlated in adults (r=0.8788; p = 0.0008) and children (r = 0.7521; p = 0.0076), and they strongly correlated with S1 and RBD-specific IgG antibodies. Conclusion: Our results provide evidence for persistent mucosal humoral memory in tonsils from previously infected and/or vaccinated adults and children against recent and old variants upon re-exposure. They also highlight the importance of targeting mucosal sites with vaccines to help control infection at the primary sites and prevent potential breakthrough infections.

A Pituitary Abscess Caused by Morganella morganii: A Case Report.

BACKGROUND Pituitary abscess (PA) is a rare pituitary lesion accounting for less than 1% of all pituitary diseases and is associated with high mortality rates. The non-specific clinical symptoms and radiological features preclude accurate diagnosis of the disease. Hence, surgical intervention is still considered the criterion standard method for PA diagnosis. Most PAs occur as a primary disease or due to complications such as surgery, sepsis, and adjacent inflamed lesions. CASE REPORT A 53-year-old man presented to the Emergency Department with a headache associated with nausea, vomiting, and constipation. The patient had no visual disturbances, polyuria, polydipsia, nocturia, or abnormal discharges. Computed tomography (CT) and magnetic resonance imaging (MRI) showed a large suprasellar mass. The patient underwent left-side trans-nasal transsphenoidal microscopic surgery for mass removal. An abscess with discharge was noticed and sent for microbiological evaluation, revealing an infection with a commensal enteric bacterium that rarely causes nosocomial infection, known as Morganella morganii. The patient was discharged after completing the intravenous antibiotic course and was given oral antibiotics. CONCLUSIONS Pituitary abscess is a rare pituitary lesion. However, taking the history of recent meningitis, sinusitis, and/or surgery may help to reach an early diagnosis, prompt surgical intervention, and vital therapeutic steps to reduce mortality rates and improve patient's outcomes. PA should always be considered when patients demonstrate signs of pituitary dysfunction associated with signs of infection. Furthermore, antibiotics should be administered immediately once the PA case is confirmed and should last for at least 6 weeks postoperatively.

Mechanistic Insight into the Enzymatic Inhibition of ß-Amyrin against Mycobacterial Rv1636: In Silico and In Vitro Approaches.

Mycobacterium tuberculosis has seen tremendous success as it has developed defenses to reside in host alveoli despite various host-related stress circumstances. Rv1636 is a universal stress protein contributing to mycobacterial survival in different host-derived stress conditions. Both ATP and cAMP can be bound with the Rv1636, and their binding actions are independent of one another. ß-Amyrin, a triterpenoid compound, is abundant in medicinal plants and has many pharmacological properties and broad therapeutic potential. The current study uses biochemical, biophysical, and computational methods to define the binding of Rv1636 with ß-Amyrin. A substantial interaction between ß-Amyrin and Rv1636 was discovered by molecular docking studies, which helped decipher the critical residues involved in the binding process. VAL60 is a crucial residue found in the complexes of both Rv1636_ß-Amyrin and Rv1636-ATP. Additionally, the Rv1636_ß-Amyrin complex was shown to be stable by molecular dynamics simulation studies (MD), with minimal changes observed during the simulation. In silico observations were further complemented by in vitro assays. Successful cloning, expression, and purification of Rv1636 were accomplished using Ni-NTA affinity chromatography. The results of the ATPase activity assay indicated that Rv1636's ATPase activity was inhibited in the presence of various ß-Amyrin concentrations. Additionally, circular dichroism spectroscopy (CD) was used to examine modifications to Rv1636 secondary structure upon binding of ß-Amyrin. Finally, isothermal titration calorimetry (ITC) advocated spontaneous binding of ß-Amyrin with Rv1636 elucidating the thermodynamics of the Rv1636_ß-Amyrin complex. Thus, the study establishes that ß-Amyrin binds to Rv1636 with a significant affinity forming a stable complex and inhibiting its ATPase activity. The present study suggests that ß-Amyrin might affect the functioning of Rv1636, which makes the bacterium vulnerable to different stress conditions.