Molecular Docking of SP40 Peptide towards Cellular Receptors for Enterovirus 71 (EV-A71)

Enterovirus 71 (EV-A71) is one of the predominant etiological agents of hand, foot and mouth disease (HMFD), which can cause severe central nervous system infections in young children. There is no clinically approved vaccine or antiviral agent against HFMD. The SP40 peptide, derived from the VP1 capsid of EV-A71, was reported to be a promising antiviral peptide that targeted the host receptor(s) involved in viral attachment or entry. So far, the mechanism of action of SP40 peptide is unknown. In this study, interactions between ten reported cell receptors of EV-A71 and the antiviral SP40 peptide were evaluated through molecular docking simulations, followed by in vitro receptor blocking with specific antibodies. The preferable binding region of each receptor to SP40 was predicted by global docking using HPEPDOCK and the cell receptor-SP40 peptide complexes were refined using FlexPepDock. Local molecular docking using GOLD (Genetic Optimization for Ligand Docking) showed that the SP40 peptide had the highest binding score to nucleolin followed by annexin A2, SCARB2 and human tryptophanyl-tRNA synthetase. The average GoldScore for 5 top-scoring models of human cyclophilin, fibronectin, human galectin, DC-SIGN and vimentin were almost similar. Analysis of the nucleolin-SP40 peptide complex showed that SP40 peptide binds to the RNA binding domains (RBDs) of nucleolin. Furthermore, receptor blocking by specific monoclonal antibody was performed for seven cell receptors of EV-A71 and the results showed that the blocking of nucleolin by anti-nucleolin alone conferred a 93% reduction in viral infectivity. Maximum viral inhibition (99.5%) occurred when SCARB2 was concurrently blocked with anti-SCARB2 and the SP40 peptide. This is the first report to reveal the mechanism of action of SP40 peptide in silico through molecular docking analysis. This study provides information on the possible binding site of SP40 peptide to EV-A71 cellular receptors. Such information could be useful to further validate the interaction of the SP40 peptide with nucleolin by site-directed mutagenesis of the nucleolin binding site.

MODULATORY ANTI- DIARRHEAL EFFECTS OF ASCORBIC ACID IN SWISS ALBINO MICE

Ascorbic acid (AA) has been reported for the management of diarrhea. The anti-diarrheal potential and modulatory activities of AA on some commonly used anti-diarrheal drugs were investigated. For this purpose, the activities of AA on castor oil-induced diarrhea in Swiss mice were examined. As standard anti-diarrheal agents, we used prazosin, propranolol, loperamide, and nifedipine with or without AA. The results revealed that AA at 25 mg/kg (i.p.) and all other standard drugs exhibited significant (p < 0.05) diarrheal attenuating activities in mice. However, the impact was more pronounced in the loperamide and propranolol groups. AA administrated with prazosin and propranolol had a higher rate of latent periods and a lower rate of diarrheic secretion during the study period (4 h) than that of the other single or mixed groups. Furthermore, a molecular docking study illustrated that AA displayed good binding affinities with (α1) (–5.2 Kcal/mol), α2b (–5.4 Kcal/mol), α2c (-5.6 Kcal/mol), β1(–5.3 Kcal/mol) and β2(–6.4 Kcal/mol) adrenoceptors. Of note, AA exerted a significant anti-diarrheal effect and it was seen to modulate the anti-diarrheal effects of α- and β-adrenergic receptor blocking agents in Swiss mice.

Immune responses to a single dose of the AZD1222/Covishield vaccine at 16 weeks in individuals in Sri Lanka

Introduction: Due to limited access to vaccines, many countries have only administered a single dose of the AZD1222, while the dosage intervals have increased ≥ weeks. We sought to investigate the immunogenicity of a single dose of vaccine at ≥ 16 weeks. Methods: SARS-CoV-2 specific antibodies in 553 individuals and antibodies to the receptor binding domain (RBD) of the Wuhan virus (WT) and the variants of concern (VOCs), ACE2 receptor blocking antibodies, ex vivo and cultured IFNγ T cell responses and B cell ELISpot responses were investigated in a sub-cohort. Results: The seropositivity rates in those >70 years of age (93.7%) was not significantly different compared to other age groups (97.7 to 98.2, Pearson Chi-Square = 7.8, p-value = 0.05). The antibody titres (antibody index) significantly declined (p<0.0001) with increase in age. 18/69 (26.1%) of individuals did not have ACE2 receptor blocking antibodies, while responses to the RBD of WT (p=0.03), B.1.1.7 (p=0.04) and B.1.617.2 (p=0.02) were significantly lower in those who were >60 years. Ex vivo IFN γ T cell ELISpot responses were seen in 10/66 (15.1%), while only a few expressed CD107a. However, >85% had a high frequency of cultured IFNγ T cell ELISpot responses and B cell ELISpots. Conclusion: Virus specific antibodies were maintained at ≥ 16 weeks after receiving a single dose of AZD1222, although levels were lower to VOCs, especially in older individuals. A single dose induced a high frequency of memory T and B cell responses.

Antibody and T cell responses to Sinopharm/BBIBP-CorV in naive and previously infected individuals in Sri Lanka

Background: As there are limited data of the immunogenicity of the Sinopharm/BBIBP-CorV in different populations, antibody responses against different SARS-CoV-2 variants of concern and T cell responses, we investigated the immunogenicity of the vaccine, in individuals in Sri Lanka. Methods: SARS-CoV-2-specific antibodies were measured in 282 individuals who were seronegative at baseline, and ACE2 receptor blocking antibodies, antibodies to the receptor binding domain (RBD) of the wild type (WT), B.1.1.7, B.1.351 and B.1.617.2, ex vivo and cultured IFNγ ELISpot assays, intracellular cytokine secretion assays and B cell ELISpot assays were carried out in a sub cohort of the vaccinees at 4 weeks and at 6 weeks (2 weeks after the second dose). Results: 95% of the vaccinees seroconverted, although the seroconversion rates were significantly lower (p<0.001) in individuals >60 years (93.3%) compared to those who were 20 to 39 years (98.9%). 81.25% had ACE2 receptor blocking antibodies at 6 weeks, and there was no difference in these antibody titres in vaccine sera compared to convalescent sera (p=0.44). Vaccinees had significantly less (p<0.0001) antibodies to the RBD of WT and B.1.1.7, although there was no difference in antibodies to the RBD of B.1.351 and B.1.617.2 compared to convalescent sera. 27.7% of 46.4% of vaccinees had ex vivo IFNγ and cultured ELISpot responses respectively, and IFNγ and CD107a responses were detected by flow cytometry. Conclusions: Sinopharm/BBIBP-CorV appeared to induce high seroconversion rates and induce a similar level of antibody responses against ACE2 receptor, B.1.617.2 and B.1.351 as seen following natural infection.

Low continuation of antipsychotic therapy in Parkinson disease – intolerance, ineffectiveness, or inertia?

Background Antipsychotics are used in Parkinson disease (PD) to treat psychosis, mood, and behavioral disturbances. Commonly used antipsychotics differ substantially in their potential to worsen motor symptoms through dopaminergic receptor blockade. Recent real-world data on the use and continuation of antipsychotic therapy in PD are lacking. The objectives of this study are to (1) examine the continuation of overall and initial antipsychotic therapy in individuals with PD and (2) determine whether continuation varies by drug dopamine receptor blocking activity. Methods We conducted a retrospective cohort study using U.S. commercially insured individuals in Optum 2001–2019. Adults aged 40 years or older with PD initiating antipsychotic therapy, with continuous insurance coverage for at least 6 months following drug initiation, were included. Exposure to pimavanserin, quetiapine, clozapine, aripiprazole, risperidone, or olanzapine was identified based on pharmacy claims. Six-month continuation of overall and initial antipsychotic therapy was estimated by time to complete discontinuation or switching to a different antipsychotic. Cox proportional hazards models evaluated factors associated with discontinuation. Results Overall, 38.6% of 3566 PD patients in our sample discontinued antipsychotic therapy after the first prescription, 61.4% continued with overall treatment within 6 months of initiation. Clozapine use was too rare to include in statistical analyses. Overall therapy discontinuation was more likely for those who initiated medications with known dopamine-receptor blocking activity (adjusted hazard ratios 1.76 [95% confidence interval 1.40–2.20] for quetiapine, 2.15 [1.61–2.86] for aripiprazole, 2.12 [1.66–2.72] for risperidone, and 2.07 [1.60–2.67] for olanzapine), compared with serotonin receptor-specific pimavanserin. Initial antipsychotic therapy discontinuation also associated with greater dopamine-receptor blocking activity medication use – adjusted hazard ratios 1.57 (1.28–1.94), 1.88 (1.43–2.46), 2.00 (1.59–2.52) and 2.03 (1.60–2.58) for quetiapine, aripiprazole, risperidone, and olanzapine, respectively, compared with pimavanserin. Similar results were observed in sensitivity analyses. Conclusions Over one-third of individuals with PD discontinued antipsychotic therapy, especially if the initial drug has greater dopamine-receptor blocking activity. Understanding the drivers of antipsychotic discontinuation, including ineffectiveness, potentially inappropriate use, clinician inertia, patient adherence and adverse effects, is needed to inform clinical management of psychosis in PD and appropriate antipsychotic use in this population.

A Grave Turn on Hashimoto’s Thyroiditis - A Case Series on Four Patients With Autoimmune Hypothyroidism that Converted to Grave’s Disease

Disclaimer: The view(s) expressed herein are those of the author(s) and do not reflect the official policy or position of Brooke Army Medical Center, the U.S. Army Medical Department, the U.S. Army Office of the Surgeon General, the Department of the Army, the Department of the Air Force, or the Department of Defense or the U.S. Government. Introduction: The most common cause of hypothyroidism is Hashimoto’s thyroiditis, a destructive autoimmune injury to the thyroid gland. Rarely, autoimmune hypothyroidism can be caused by thyroid-stimulating hormone (TSH) receptor blocking antibodies (TSHRab), and can be difficult to differentiate clinically from Hashimoto’s. Grave’s disease is the most common etiology of hyperthyroidism, and is typically caused by activation from TSHRab acting as an agonist for the TSH receptor. Patients with autoimmune thyroiditis, whether from TSHRab or Hashimoto’s, have been infrequently reported to convert to Grave’s disease1–3. Presentation: We present four cases whom initially presented with typical symptoms of hypothyroidism, were diagnosed with autoimmune hypothyroidism and started on levothyroxine. All four cases were later found to be hyperthyroid and ultimately diagnosed and treated for Grave’s disease. Conclusion: Primary hypothyroidism can rarely transition to a hyperthyroid state, although these cases may be underreported. The mechanism isn’t well understood, but is hypothesized to be from a switch of a predominance of TSH receptor blocking antibodies (TBAb) to that of thyroid stimulating antibodies (TSAb)1. Assays using competitive binding for TSH receptor antibodies will not differentiate between blocking and stimulating antibodies4. A high index of suspicion is needed to diagnose these individuals. References: 1. McLachlan SM, Rapoport B. Thyrotropin-blocking autoantibodies and thyroid-stimulating autoantibodies: Potential mechanisms involved in the pendulum swinging from hypothyroidism to hyperthyroidism or vice versa. Thyroid. 2013;23(1). doi:10.1089/thy.2012.03742. Takasu N, Matsushita M. Changes of TSH-stimulation blocking antibody (TSBAb) and thyroid stimulating antibody (TSAb) over 10 years in 34 TSBAb-positive patients with hypothyroidism and in 98 TSAb-positive graves’ patients with hyperthyroidism: Reevaluation of TSBAb and TSAb in TSH-receptor-antibody (TRAb)-positive patients. J Thyroid Res. 2012;2012. doi:10.1155/2012/1821763. Gonzalez-Aguilera B, Betea D, Lutteri L, et al. Conversion to graves disease from hashimoto thyroiditis: A study of 24 patients. Arch Endocrinol Metab. 2018;62(6). doi:10.20945/2359-39970000000864. Li Y, Kim J, Diana T, Klasen R, Olivo PD, Kahaly GJ. A novel bioassay for anti-thyrotrophin receptor autoantibodies detects both thyroid-blocking and stimulating activity. Clin Exp Immunol. 2013;173(3). doi:10.1111/cei.12129