Drug discovery and development against coronavirus disease 2019 (COVID-19) is the utmost need and the most challenging task of the hour. Many research groups from different countries are working continuously in this direction, and till 8 March 2020, a total of 382 clinical trials have been registered on the WHO’s International Clinical Trials Registry Platform [1]. There is an urgent need to identify specific targets to design promising therapeutic agents against severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2), the virus that causes COVID-19. Analysis of SARS-CoV-2 reveals seven major target proteins that can be considered for drug design against the virus. These include the spike, envelope, membrane, nucleocapsid, protease, hemagglutinin esterase and helicase [2, 3]. Beyond these, several Non Structural Proteins (NSPs) can also be evaluated as targets for drug development [4]. There are only a few Protein Data Bank (PDB) Ids available related to SARS-CoV-2 in the RCSB database. Table 1 summarizes recently released PDB Ids (from 5.2.2020 to 25.3.2020) for various SARS-CoV-2 targets [5].
The host range of a virus is defined as the number of species a virus potentially infects. The specialist virus infects one or few related species while the generalist virus infects several different species, possibly in different families. Origin of generalist viruses from their specialist nature and the expansion of the host range of the generalist virus occur with the host shift event in which the virus encounters and adapts to a new host. Host shift events have resulted in the majority of the newly emerging viral diseases. This review discusses the advantages and disadvantages of generalist over specialist viruses and the unique features of plant viruses and their hosts that result in a higher incidence of generalist viruses in plants.
Although there is continuous work in progress in some of the above mentioned approaches, but there is still no drug/vaccine available to treat COVID-19 Drug repurposing offers an economical and rapid strategy to discover a potential therapeutic agent in the current hectic situation This compilation may be helpful to the researchers, drug developers and health agencies to look into the matter and work against the possible targets to develop a therapeutic candidate against COVID-19 The challenge associated with drug repurposing is the inadequate efficacy of single therapeutic candidate Another complication associated with this approach is to search and analyze the huge amount of previously reported data to make efficient and effective use against a new indication The complex/unclear events of the pathophysiology of SARS-CoV-2 also offer a great challenge to select a candidate for repurposing
Introduction: The common cold syndrome of acute upper respiratory tract viral infection is the most common disease among mankind and is an extremely common illness in children. There is a great need for a safe and effective antiviral treatment with minimal side effects. The challenge in developing a treatment is the numerous and varied respiratory viruses that cause this common illness and the need for a treatment with good tolerability and safety. Explanation: All respiratory viruses must reach the cell surface by passing through respiratory fluid and mucus, and this common feature may allow for the development of antivirals that capture viruses during this transit. This article discusses how large polyanionic molecules such as iota-carrageenan may trap positively charged respiratory viruses. Iota-carrageenan is a large polysaccharide molecule which is neither absorbed from the respiratory tract nor metabolised. It, therefore, does not have any pharmacological properties. Iota-carrageenan nasal spray has been shown to reduce the titres of respiratory viruses and to reduce the severity of symptoms in placebo-controlled clinical trials, including children and adults. The results of four clinical trials are presented. Conclusion: Iota-carrageenan is a good candidate as a safe and effective non-specific antiviral treatment for common cold, and more research is justified on polyanionic molecules like carrageenans as antivirals.
Evolutionary biology has become one of the imperative determinants explaining the origin of several viruses which were either identified decades back or are recognized lately using metagenomic approaches. Several notifiable emerging viruses like influenza, Severe Acute Respiratory Syndrome (SARS), Middle East Respiratory Syndrome (MERS), Ebola, Hendra, Nipah and Zika viruses have become the leading causes of epidemics and losses thereto in both human and animals. The sufferings are higher due to gastroenteritis causing viruses including Astrovirus, Calicivirus, Enterovirus, Kobuvirus Picobirnavirus, Sapelovirus, Teschovirus, and many more. Notably, the majority of the emerging viruses enclose RNA genome and these are more prone for insertions/mutation in their genome, leading to evolving viral variants. Rapidity in viral evolution becomes a big hitch in the development process of successful vaccines or antiviral. The prominent gastroenteric virus is rotavirus, which is a double-stranded RNA virus with a segmented nature of genome enabling higher reassortment events and generates unusual strains with unique genomic constellations derivative of parental rotavirus strains. Although most rotaviruses appear to be host restricted, the interspecies transmission of rotaviruses has been well documented across the globe. The nocturnal bats have been accepted harbouring many pathogenic viruses and serving as natural reservoirs. Indications are that bats can also harbour rotaviruses, and help in virus spread. The zooanthroponotic and anthropozoonotic potential of rotaviruses has significant implications for rotavirus epidemiology. Hitherto reports confirm infection of humans through rotaviruses of animal origin, exclusively via direct transmission or through gene reassortments between animal and human strain of rotaviruses. There is a need to understand the ecology and evolutionary biology of emerging rotavirus strains to design effective control programs.
