Since the first described human infection with SARS-CoV-2 in December of 2019 many subunit protein vaccines have been proposed for use in humans. Subunit vaccines use one or more antigens suitable for eliciting a robust immune response. However, the major concern is the efficacy of subunit vaccines and elicited antibodies to neutralize the variants of SARS-CoV-2 like B.1.1.7 (Alpha), B.1.351 (Beta) and P1 (Gamma), B.1.617 (Delta) and C.37 (Lambda). The Spike protein (S) is a potential fragment for use as an antigen in vaccine development. This protein plays a crucial role in the first step of the infection process, as it binds to Angiotensin-Converting Enzyme 2 (ACE2) receptor and enters the host cell after binding. Immunization-induced specific antibodies against the receptor binding domain (RBD) may block and effectively prevent virus invasion. The focus of this review is the impact of spike mutated variants of SARS-CoV2 (Alpha, Beta, Gamma, Delta, and Lambda) on the efficacy of subunit recombinant vaccines. To date, a low or no significant impact on vaccine efficacy against Alpha and Delta variants has been reported. Such an impact on vaccine efficacy for Beta, Delta, Gamma, and Lambda variants may be even greater compared to the Alpha variant. Nonetheless, more comprehensive analyses are needed to assess the real impact on vaccine efficacy brought about by SARS-CoV-2 variants.

Background: Carbapenem-resistant Klebsiella pneumoniae (CRKP) is a significant clinical problem, given the lack of therapeutic options. The CRKP strains have emerged as an essential worldwide healthcare issue during the last 10 years. Global expansion of the CRKP has made it a significant public health hazard. We must consider to novel therapeutic techniques. Bacteriophages are potent restorative cases against infections with multiple drug-resistant bacteria. The Phages offer promising prospects for the treatment of CRKP infections. Objective: In this study, a novel K. pneumoniae phage vB_KshKPC-M was isolated, characterized, and sequenced, which was able to infect and lyse Carbapenem-resistant K. pneumoniae host specifically. Methods: One hundred clinical isolates of K. pneumoniae were collected from patients with COVID-19 associated with ventilator-associated acute pneumonia hospitalized at Shahid Beheshti Hospital, Kashan, Iran, from 2020 to 2021. Initially, all samples were cultured, and bacterial isolates identified by conventional biochemical tests, and then the ureD gene was used by PCR to confirm the isolates. The Antibiotic susceptibility test in the disc diffusion method and Minimum inhibitory concentrations for Colistin was done and interpreted according to guidelines. Phenotypic and molecular methods determined the Carbapenem resistance of isolates. The blaKPC, blaNDM, and blaOXA-23 genes were amplified for this detection. Biofilm determination of CRKP isolates was performed using a quantitative microtiter plate (MTP) method. The phage was isolated from wastewater during the summer season at a specific position from Beheshti Hospital (Kashan, Iran). The sample was processed and purified against the bacterial host, a CRKP strain isolated from a patient suffering from COVID-19 pneumoniae and resistance to Colistin with high potency for biofilm production. This isolate is called Kp100. The separated phages were diluted and titration by the double overlay agar plaque assay. The separate Phage is concentrated with 10% PEG and stored at −80 °C until use. The phage host range was identified by the spot test method. The purified phage morphology was determined using a transmission electron microscope. The phage stability tests (pH and temperature) were analyzed. The effect of cationic ions on phage adsorption was evaluated. The optimal titer of bacteriophage was determined to reduce the concentration of the CRKP strain. One-step growth assays were performed to identify the purified phage burst’s latent cycle and size. The SDS-PAGE was used for phage proteins analysis. Phage DNA was extracted by chloroform technique, and the whole genome of lytic phage was sequenced using Illumina HiSeq technology (Illumina, San Diego, CA). For quality assurance and preprocessing, such as trimming, Geneious Prime 2021.2.2 and Spades 3.9.0. The whole genome sequence of the lytic phage is linked to the GenBank database accession number. RASTtk—v1.073 was used to predict and annotate the ORFs. Prediction of ORF was performed using PHASTER software. ResFinder is used to assess the presence of antimicrobial resistance and virulence genes in the genome. The tRNAs can-SE v2.0.6 is used to determine the presence of tRNA in the genome. Linear genome comparisons of phages and visualization of coding regions were performed using Easyfig 2.2.3 and Mauve 2.4.0. Phage lifestyles were predicted using the program PHACTS. Phylogenetic analysis and amino acid sequences of phage core proteins, such as the major capsid protein. Phylogenies were reconstructed using the Neighbor-Joining method with 1000 bootstrap repeat. HHpred software was used to predict depolymerase. In this study, GraphPad Prism version 9.1 was used for the statistical analysis. Student’s t-test was used to compare the sets and the control sets, and the significance level was set at P ≤ 0.05. Results: Phage vB_KshKPC-M is assigned to the Siphoviridae, order Caudovirales. It was identified as a linear double-stranded DNA phage of 54,378 bp with 50.08% G + C content, had a relatively broad host range (97.7%), a short latency of 20 min, and a high burst size of 260 PFU/cell, and was maintained stable at different pH (3–11) and temperature (45–65 °C). The vB_KshKPC-M genome contains 91 open-reading frames. No tRNA, antibiotic resistance, toxin, virulence-related genes, or lysogen-forming gene clusters were detected in the phage genome. Comparative genomic analysis revealed that phage vB_KshKPC-M has sequence similarity to the Klebsiella phages, phage 13 (NC_049844.1), phage Sushi (NC_028774.1), phage vB_KpnD_PeteCarol (OL539448.1) and phage PWKp14 (MZ634345.1). Conclusion: The broad host range and antibacterial activity make it a promising candidate for future phage therapy applications. The isolated phage was able to lyse most of the antibiotic-resistant clinical isolates. Therefore, this phage can be used alone or as a phage mixture in future studies to control and inhibit respiratory infections caused by these bacteria, especially in treating respiratory infections caused by resistant strains in sick patients.

Novel coronaviruses (CoVs) are zoonotic pathogens, but the first human-to-human transmission has been reported. CoVs have the best known genome of all RNA viruses, and mutations in the genome have now been found. A pneumonia of unknown cause detected in Wuhan, China, was first reported to the WHO Country Office in China on 31 December 2019. This study aims to report early findings related to COVID-19 and provide methods to prevent and treat it.

The single-stranded DNA virus known as human bocavirus 1 (HBoV-1) is an icosahedral, linear member of the Parvoviridae family. In 2005, it was discovered in nasopharyngeal samples taken from kids who had respiratory tract illnesses. The HBoV genome is 4.7–5.7 kb in total length. The HBoV genome comprises three open-reading frames (ORF1, ORF2, and ORF3) that express structural proteins (VP1, VP2, and VP3), viral non-coding RNA, and non-structural proteins (NS1, NS1-70, NS2, NS3, and NP1) (BocaSR). The NS1 and NP1 are crucial for viral DNA replication and are substantially conserved proteins. Replication of the HBoV-1 genome in non-dividing, polarized airway epithelial cells. In vitro, HBoV-1 infects human airway epithelial cells that are strongly differentiated or polarized. Young children who have HBoV-1 are at risk for developing a wide range of respiratory illnesses, such as the common cold, acute otitis media, pneumonia, and bronchiolitis. The most common clinical symptoms are wheezing, coughing, dyspnea, and rhinorrhea. After infection, HBoV-1 DNA can continue to be present in airway secretions for months. The prevalence of coinfections is considerable, and the clinical symptoms can be more severe than those linked to mono-infections. HBoV-1 is frequently detected in combination with other pathogens in various reports. The fecal-oral and respiratory pathways are more likely to be used for HBoV-1 transmission. HBoV-1 is endemic; it tends to peak in the winter and spring. This Review summarizes the knowledge on HBoV-1.