Small Drugs, Huge Impact: The Extraordinary Impact of Antisense Oligonucleotides in Research and Drug Development

Antisense oligonucleotides (ASOs) are an increasingly represented class of drugs. These small sequences of nucleotides are designed to precisely target other oligonucleotides, usually RNA species, and are modified to protect them from degradation by nucleases. Their specificity is due to their sequence, so it is possible to target any RNA sequence that is already known. These molecules are very versatile and adaptable given that their sequence and chemistry can be custom manufactured. Based on the chemistry being used, their activity may significantly change and their effects on cell function and phenotypes can differ dramatically. While some will cause the target RNA to decay, others will only bind to the target and act as a steric blocker. Their incredible versatility is the key to manipulating several aspects of nucleic acid function as well as their process, and alter the transcriptome profile of a specific cell type or tissue. For example, they can be used to modify splicing or mask specific sites on a target. The entire design rather than just the sequence is essential to ensuring the specificity of the ASO to its target. Thus, it is vitally important to ensure that the complete process of drug design and testing is taken into account. ASOs’ adaptability is a considerable advantage, and over the past decades has allowed multiple new drugs to be approved. This, in turn, has had a significant and positive impact on patient lives. Given current challenges presented by the COVID-19 pandemic, it is necessary to find new therapeutic strategies that would complement the vaccination efforts being used across the globe. ASOs may be a very powerful tool that can be used to target the virus RNA and provide a therapeutic paradigm. The proof of the efficacy of ASOs as an anti-viral agent is long-standing, yet no molecule currently has FDA approval. The emergence and widespread use of RNA vaccines during this health crisis might provide an ideal opportunity to develop the first anti-viral ASOs on the market. In this review, we describe the story of ASOs, the different characteristics of their chemistry, and how their characteristics translate into research and as a clinical tool.

Simulation of COVID-19 Symptoms in a Genetically Engineered Mouse Model

The ongoing infectious viral disease pandemic (also known as the coronavirus disease-19; COVID-19) by a constantly emerging viral agent commonly referred as the severe acute respiratory syndrome corona virus 2 or SARS-CoV-2 has revealed unique pathological findings from infected human beings, and the postmortem observations. The list of disease symptoms, and post-mortem observations is too long to mention; however, a few notable ones are worth mentioning to put into a perspective in understanding the malignity of this pandemic starting with respiratory distress or dyspnea, chest congestion, muscle or body aches, malaise, fever, chills, etc. We opine that further improvement for delivering highly effective treatment, and preventive strategies would be benefited from validated animal disease models. In this context, we designed a study and show that a genetically engineered mouse expressing the human angiotensin converting enzyme 2; hACE2 (the receptor used by SARS-CoV-2 agent to enter host cells) represents an excellent investigative resource in simulating important clinical features of the COVID-19 infection. The hACE2 mouse model (which is susceptible to SARS-CoV-2) when administered with a recombinant SARS-CoV-2 spike (S) protein intranasally exhibited a profound cytokine storm capable of altering the physiological parameters including significant changes in in vivo cardiac function along with multi-organ damage that was further confirmed via histological findings. More importantly, visceral organs from SARS-CoV-2 spike (S) treated mice revealed thrombotic blood clots as seen during postmortem examination of the mice. Thus, the hACE2 engineered mouse appears to be a suitable model for studying intimate viral pathogenesis paving the way for further identification, and characterization of appropriate prophylactics as well as therapeutics for COVID-19 management.

Investigation of Children with Acute Gastroenteritis by Multiplex PCR Method in Central Part of Turkey

Objective Gastroenteritis is a disease that affects all age groups, especially children, and causes high mortality and morbidity in all countries. The most common agents of acute gastroenteritis are viral agents. As a result, millions of diarrhea attacks and hospital admissions occur worldwide every year due to viral gastroenteritis. This study uses the multiplex polymerase chain reaction (PCR) method to investigate the viruses that are the causative agents of viral gastroenteritis in the pediatric patient group in Konya, Turkey. Methods Stool samples of 94 patients aged 0 to 18 years sent from Emergency clinics and Pediatric outpatient clinics, Meram Medical Faculty Hospital Pediatric clinics, Konya Necmettin Erbakan University to Medical Microbiology Laboratory with a diagnosis of gastroenteritis between February and December 2018 were included in the study. Stool samples were stored at –80°C until the time of the analysis. Deoxyribonucleic acid/ribonucleic acid isolation from stool samples was performed with EZ1 Virus Mini Kit v2.0 (Qiagen, Hilden, Germany) using an automatic extraction system (BioRobot EZ1 system, Qiagen). The presence of astrovirus, rotavirus, adenovirus, norovirus (GI, GII), and sapovirus agents was investigated by the multiplex PCR method (Fast Track Diagnostics, Luxembourg) viral gastroenteritis kit. Results Viral gastroenteritis agents were detected in 56.3% of the patients. One viral agent was detected in 47 (50%) of these patients and at least two viral agents in 6 (6.3%) of them. Norovirus GII was detected in 20 (21.2%) of the children included in the study, adenovirus in 13 (13.8%), rotavirus in 11 (12.8%), astrovirus in 11 (11.7%), sapovirus in 4 (4.2%), and norovirus GI in 1 (1.06%). When the distribution of viral agents was examined by months, the most number of agents were observed (21; 35%) in May, followed by April and June (12; 20%). Considering the distribution of the prevalence of the agents by age, it was seen to be mainly between 0 and 12 months (42%). Conclusion Considering that the most common viral agent in our region is norovirus GII, it will be useful to investigate the norovirus that is not routinely examined in children who are admitted to clinics with the complaint of gastroenteritis. It will be appropriate to examine routinely adenovirus, rotavirus, and norovirus in the laboratory, especially in children with diarrhea and vomiting in the winter and spring months.

Recent advances in nanotechnology-based COVID-19 vaccines and therapeutic antibodies

COVID-19 has caused a global pandemic and millions of deaths. It is imperative to develop effective countermeasures against the causative viral agent, SARS-CoV-2 and its many variants. Vaccines and therapeutic...

Potential Neurocognitive Symptoms Due to Respiratory Syncytial Virus Infection

Respiratory infections are among the major public health burdens, especially during winter. Along these lines, the human respiratory syncytial virus (hRSV) is the principal viral agent causing acute lower respiratory tract infections leading to hospitalization. The pulmonary manifestations due to hRSV infection are bronchiolitis and pneumonia, where the population most affected are infants and the elderly. However, recent evidence suggests that hRSV infection can impact the mother and fetus during pregnancy. Studies have indicated that hRSV can infect different cell types from the placenta and even cross the placenta barrier and infect the fetus. In addition, it is known that infections during the gestational period can lead to severe consequences for the development of the fetus due not only to a direct viral infection but also because of maternal immune activation (MIA). Furthermore, it has been described that the development of the central nervous system (CNS) of the fetus can be affected by the inflammatory environment of the uterus caused by viral infections. Increasing evidence supports the notion that hRSV could invade the CNS and infect nervous cells, such as microglia, neurons, and astrocytes, promoting neuroinflammation. Moreover, it has been described that the hRSV infection can provoke neurological manifestations, including cognitive impairment and behavioral alterations. Here, we will review the potential effect of hRSV in brain development and the potential long-term neurological sequelae.

First Detection of Rotavirus C in Asymptomatic Pigs from India with Unexpected Dominance and Characterization of the Structural and Nonstructural Genes

Epidemiological and molecular investigation was conducted on Rotavirus C (RVC), the viral agent documented with rising prevalence rate, disease severity and cross species transmission and large outbreak potential. Fecal specimens of pigs collected from two cities of Maharashtra state, India tested for RVC showed 20.1% detection rate with majority below 3 months of age. No significant difference in detection rates was observed in the specimens collected in 2009 from Northern and in 2013 from Western parts of Maharashtra. The phylogenetic analyses showed presence of the I7 and I10 genotypes of the VP6 gene and representative strains with G1 and E5 genotypes of the VP7 and NSP4 gene respectively. Full genome characterization of a single strain showed presence of G1, P1, I7, R1, C1, M3, A1, N5, T5, E5, H1 genotypes of the VP7, VP4, VP6, VP1, VP2, VP3, NSP1, NSP2, NSP3, NSP4 and NSP5 genes respectively. This is the first evidence of detection of porcine RVC in asymptomatic pigs in India as well as with highest detection rate reported in asymptomatic pigs till date globally. Identification of porcine RVC at two time intervals and two different parts of Maharashtra state indicates the possibility of continuous circulation of RVC in pig population through asymptomatic infections.

First Report of citrus virus A in Texas associated with oak leaf patterns in Citrus sinensis

In 2018, Navarro et al. (2018a, b) identified two new negative sense coguviruses in citrus, citrus concave gum-associated virus (CCGaV) and citrus virus A (CiVA). Since then, the members of the genus Coguvirus have been also detected in other plant species (Xin et al. 2017; Wright et al. 2018; Svanella-Duma et al. 2019). In 2016, leaf flecking with oak leaf patterns were observed in five plants among embryo-rescued navel orange (NO) (Citrus sinensis (L.) Osbeck) trees grafted on C22 (C. sunki x Poncirus trifoliata) rootstock, maintained in a shade house. Madam Vinous (MV) sweet orange trees graft-inoculated with blind buds from the symptomatic NO plants developed the same symptoms in the new growth. These symptoms were similar to those on the citrus concave gum (CG) source tree of the California isolate CG301, one of the standard citrus disease isolates used as a positive control for biological indexing (Roistacher et al. 2000). None of the trees with oak leaf symptoms tested positive with reverse transcription (RT)-PCR for a panel of viruses and viroids commonly infecting citrus (Table S1) . In this study, CG301 leaf RNA-Seq data was used as a platform to identify any viral agent(s) associated with the oak leaf symptoms observed in the symptomatic NO trees (Fig. S1). Of ~162.8 million paired-end CG301 RNA-Seq reads (150 bp), de novo assembly of ~9.6 million reads, not mapped to C. sinensis genome (v.1.1), yielded 5,375 contigs. BLASTn using NCBI virus database (txid 10239) identified two contigs, #49 (6,715 nt) and #20 (2,764 nt), which exhibited ~96% sequence identity, respectively, to RNA1 and 2 of CiVA isolate W4 (MG764565; MG764566) and 71-73% identity to that of CCGaV isolate CGW2 (KX960112; KX960111). 5'-Nuclease assay developed based on contig #20 detected coguviral sequences in the five symptomatic NO and graft-inoculated MV trees as well as in CG301 but not in 44 asymptomatic field trees located near the shade house where the symptomatic NO trees had been kept. A full genomic sequence of the coguviruses present in CG301 and a symptomatic NO tree was reconstructed by RT-PCR. Both CG301 and NO isolate have a 6689 nt long negative sense RNA1 (MT922052; MK689372) encoding RNA-dependent RNA polymerase (RdRp) and a 2739 nt long ambisense RNA2 (MT922053; MK689373) encoding movement protein (MP) and nucleocapsid protein (NP). The isolate CG301 and NO share ~96% nucleotide sequence identity. The genome of both CG301 and NO isolate share 95.4-97.8 % sequence identity to that of CiVA isolate W4 and 70-72.9 % sequence identity to CCGaV isolate CGW2. BLASTp showed that RdRp of CG301 and NO isolate have 96.3-97.7 % sequence identity to CiVA W4 RdRp and ~77 % to CCGaV CGW2 RdRp. These data indicated the presence of CiVA in the symptomatic NO trees and in the concave gum source tree CG301. Recent reports of CiVA in South Africa and Greece indicated a potential wider distribution of CiVA in various citrus growing regions that may be associated with two graft-transmissible citrus diseases, citrus concave gum and impietratura disease (Roistacher et al. 2000; Velázquez et al. 2019; Beris et al. 2021; Bester et al. 2021). Although the source of CiVA in the symptomatic NO trees and the degree of CiVA prevalence in Texas had not been determined yet, a possible involvement of vector(s) or other means of spread (e.g. seed transmission) cannot be ruled out (Timmer et al. 2017). The current study demonstrated the need for further studies to determine the level of threat of coguviruses for citrus production in Texas.

Role of ARP2/3 Complex-Driven Actin Polymerization in RSV Infection

Respiratory syncytial virus (RSV) is the leading viral agent causing bronchiolitis and pneumonia in children under five years old worldwide. The RSV infection cycle starts with macropinocytosis-based entry into the host airway epithelial cell membrane, followed by virus transcription, replication, assembly, budding, and spread. It is not surprising that the host actin cytoskeleton contributes to different stages of the RSV replication cycle. RSV modulates actin-related protein 2/3 (ARP2/3) complex-driven actin polymerization for a robust filopodia induction on the infected lung epithelial A549 cells, which contributes to the virus’s budding, and cell-to-cell spread. Thus, a comprehensive understanding of RSV-induced cytoskeletal modulation and its role in lung pathobiology may identify novel intervention strategies. This review will focus on the role of the ARP2/3 complex in RSV’s pathogenesis and possible therapeutic targets to the ARP2/3 complex for RSV.

A critical analysis about the supposed role of azithromycin in the treatment of covid-19

After over one year, the coronavirus disease 2019 (covid-19) has still affected millions of people. For this reason, global efforts to promote better treatment of covid-19 have been undertaken focused on the repurposing of existing medications.In Brazil, azithromycin, a broad-spectrum antibiotic, has been used in association with other drugs as an immunomodulatory, anti-inflammatory, and anti-viral agent, regardless of bacterial co-infection. Indeed, data from experimental studies have demonstrated the capacity of this drug in reducing the production of infection-induced pro-inflammatory cytokines, such as IL-8, IL-6, and TNF-alpha. However, observational studies revealed conflicting results regarding its effect, whereas well-conducted clinical trials have not shown a considerable effect of this agent on the improvement of clinical outcomes. This narrative review addressed the possible role of this antibiotic in the management of covid-19, based on data from clinical and preclinical studies.