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The epidemic of coronavirus disease 2019 (COVID-19) was caused by the severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2). The spike (S) protein of SARS-Cov-2 is composed of two subunits, S1 and S2. This study aimed to describe SARS-CoV-2 haplotypes in Iranians based on the S gene, which plays a key role in the receptor recognition and cell membrane fusion proses. 95 positive saliva samples for SARS-CoV-2 were amplified and sequenced for the S gene. The sequences were classified into 35 haplotypes, which 11 haplotypes were new (H1, H2, H3, H4, H6, H7, H11, H13, H15, H16, H25) and have not been reported so far. Amino acid substitutions were found at 40 positions that 23 were located at S1 subunit and 16 were at S2 subunit and one was at cleavage loop (P681H/R), thus polymorphisms at S1 subunit were found to be higher than S2. The neutrality index (NI) analyses showed a negative departure from the neutral substitution patterns (NI > 1) for S1 and S2 subunit in the studied sequences. The co-occurrence of B-cell epitopes and mutation sites were found in seven positions with more probably to be exposed the immune system pressure. In conclusion, the results provide the significant data to design an effective vaccine based on this protein., Competing Interests: Declaration of Competing Interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (Copyright © 2023 The Author(s). Published by Elsevier B.V. All rights reserved.)

Morphine and tramadol are the opioid analgesic drugs acting via activation of μ‑opioid receptors. It is important to understand which mechanism (synergistic or additive anti‑nociceptive activity) induced potent anti‑nociceptive effect by co‑administration of morphine and tramadol. Identification of new strategies that can potentiate analgesic effects of opioids will be good therapeutic approaches for pain relief. To this aim, male mice were cannulated in the left ventricle by a stereotaxic instrument. A tail‑flick test was used to record the pain threshold. The results revealed that intracerebroventricularly injection of morphine induced an anti‑nociceptive effect in non‑sensitized and morphine‑sensitized mice. We found that infusion of tramadol produced an anti‑nociceptive response in non‑sensitized mice, whereas tramadol in doses of 0.5 and 1 μg/mouse induced analgesia in morphine‑sensitized mice. Co‑injection of a non‑effective dose of tramadol or morphine (0.25 μg/mouse) with different doses of morphine or tramadol (0.25, 0.5, and 1 μg/mouse) respectively potentiated the analgesic effect of the previous drug. An isobolographic analysis of data was performed, indicating a synergistic interaction between morphine and tramadol in non‑sensitized and morphine‑sensitized mice. Our data indicated that both morphine and tramadol elicit more anti‑nociceptive response in morphine sensitized mice; there is a synergistic effect between morphine and tramadol upon induction of analgesic effect in non‑sensitized and morphine‑sensitized mice.

Apical membrane antigen-1 (AMA-1) of Plasmodium vivax Grassi et Feletti, 1890 is a promising malaria vaccine candidate. However, antigenic variation is a major problem to design a universal malaria vaccine. Hence, detailed understanding of the pvama-1 gene polymorphism can provide conductive information on this potential vaccine component. Therefore, this study investigated the extent of genetic polymorphisms at domain I (DI), DII and partial DIII of AMA-1 among Iranian P. vivax isolates. Out of 107 blood samples, 92 were analysed based on the quality of the sequencing data. The sequences were classified into 53 haplotypes. Amino acid changes were observed at 31 positions that 17 were located at DI, 11 were at DII and the rest of them (3 positions) were at DIII. Thus, codon polymorphisms at DI were found to be higher than DII. Also, five of these polymorphic codons (D242E, T374P, S389R, Y391F, I395F) were novel and have not been reported yet. Neutrality analysis by using the dN-dS difference (the difference between the rate of non-synonymous and synonymous mutations) showed a negative diversifying selection at DI, DII and across the length of both domains. The potential B-cell epitopes were found in 5 regions of the PvAMA-1 with 10 mutation sites (E145A, K188N, E189N/K/D, K190Q/E, P210S, E227V, D242E, R249H, G253E, K352E), whereas only one mutation (G288E) has been detected in intrinsically unstructured/disordered regions. Fixation index (Fst) estimation between Iranian and Indian isolates (0.0131) indicated a significant low genetic differentiation. Distribution of the polymorphic sites and IURs mapped on a three dimensional structure of PvAMA-1 showed that these regions were located at two opposite faces of the molecule. In conclusion, the results have significant value in the design and development of a malaria vaccine based on this antigen.