Leishmania (L.) tropica is the causative agent of different forms of human leishmaniasis. There is little information about the role of Leishmania-specific antibodies in the immune response against L. tropica infection. The aim of this study is to evaluate the role of Leishmania-specific antibodies and their immunoglobulin G (IgG) isotypes in L. tropica infection. L. tropica at two different doses (high dose, 106 parasites/mouse and low dose, 103 parasites/mouse) were used for infection of BALB/c mice. BALB/c mice infected with Leishmania major were used for comparison. Anti-Leishmania antibodies of the IgG1 and IgG2a isotypes were assayed by enzyme-linked immunosorbent assay. Our data showed that (1) a higher parasite dose results in higher levels of antibody. (2) L. tropica infection results in a lower IgG1 antibody response, compared with L. major infection. (3) The IgG2a/IgG1 antibody response in L. tropica infection is higher than that in L. major infection. A higher IgG2a/IgG1 ratio is associated with protective immune response in L. tropica infection. These data can help to approach the complex profile of immunity against L. tropica infection.

Introduction: There are currently no specific drugs and universal vaccines for Coronavirus disease 2019 (COVID-19), hence urgent effective measures are needed to discover and develop therapeutic agents. Applying peptide therapeutics and their related compounds is a promising strategy to achieve this goal. This review is written based on the literature search using several databases, previous studies, scientific reports, our current knowledge about the antimicrobial peptides (AMPs), and our personal analyses on the potential of the antiviral peptides for the treatment of COVID-19. Areas covered: In this review, we begin with a brief description of SARS-CoV2 followed by a comprehensive description of antiviral peptides (AVPs) including natural and synthetic AMPs or AVPs and peptidomimetics. Subsequently, the structural features, mechanisms of action, limitations, and therapeutic applications of these peptides are explained. Expert opinion: Regarding the lack and the limitations of drugs against COVID-19, AMPs, AVPs, and other peptide-like compounds such as peptidomimetics have captured the attention of researchers due to their potential antiviral activities. Some of these compounds comprise unique properties and have demonstrated the potential to fight SARS-CoV2, particularly melittin, lactoferrin, enfuvirtide, and rupintrivir that have the potential to enter animal and clinical trials for the treatment of COVID-19.

Introduction: Antibiotic-associated diarrhea (AAD) is a major hospital problem and a common adverse effect of antibiotic treatment. The aim of this study was to investigate the prevalence of the most important bacteria that cause AAD in hospitalized patients.Materials and methods: PubMed, Web of Science and Scopus databases were searched using multiple relevant keywords and screening carried out based on inclusion/exclusion criteria from March 2001 to October 2021. The random-effects model was used to conduct the meta-analysis.Results: Of the 7,377 identified articles, 56 met the inclusion criteria. Pooling all studies, the prevalence ofClostridioides(Clostridium)difficile,Clostridium perfringens,Klebsiella oxytoca, andStaphylococcus aureusas AAD-related bacteria among hospitalized patients were 19.6%, 14.9%, 27%, and 5.2%, respectively. The prevalence of all four bacteria was higher in Europe compared to other continents. The highest resistance ofC.difficilewas estimated to ciprofloxacin and the lowest resistances were reported to chloramphenicol, vancomycin, and metronidazole. There was no or little data on antibiotic resistance of other bacteria.Conclusions: The results of this study emphasize the need for a surveillance program, as well as timely public and hospital health measures in order to control and treat AAD infections.

Regarding the urgency of therapeutic measures for coronavirus disease 2019 (COVID-19) pandemic, the use of available drugs with FDA approval is preferred because of the less time and cost required for their development. In silico drug repurposing is an accurate way to speed up the screening of the existing FDA-approved drugs to find a therapeutic option for COVID-19. The similarity in SARS-CoV-2 and HIV-1 fusion mechanism to host cells can be a key point for Inhibit SARS-CoV-2 entry into host cells by HIV fusion inhibitors. Accordingly, in this study, an HIV-1 fusion inhibitor called Enfuvirtide (Enf) was selected. The affinity and essential residues involving in the Enf binding to the S2 protein of SARS-CoV-2, HIV-1 gp41 protein and angiotensin-converting enzyme 2 (ACE-2) as a negative control, was evaluated using molecular docking. Eventually, Enf-S2 and Enf-gp41 protein complexes were simulated by molecular dynamics (MD) in terms of binding affinity and stability. Based on the most important criteria such as docking score, cluster size, energy and dissociation constant, the strongest interaction was observed between Enf with the S2 protein. In addition, MD results confirmed that Enf-S2 protein interaction was remarkably stable and caused the S2 protein residues to undergo the fewest fluctuations. In conclusion, it can be stated that Enf can act as a strong SARS-CoV-2 fusion inhibitor and demonstrates the potential to enter the clinical trial phase of COVID-19. Communicated by Ramaswamy H. Sarma