Sm Faysal Bellah, Department of Pharmacy, Manarat International University, Dhaka-1216, Bangladesh.
Sm Faysal Bellah and Md. Rashidul Islam. (2024). Antiviral Treatments for Dengue Virus Infections: A Comprehensive Review. Pharmacy and Drug Development. 3(2). DOI:10.58489/2836-2322/034
© 2024 Sm Faysal Bellah, this is an open-access article distributed under the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.
Dengue virus, viral infections and antiviral drug
Dengue virus is a human pathogen that infects roughly 390 million people each year, with a quarter of them developing clinical symptoms. Although progress has been made in understanding the biology of dengue fever, there is still no licensed vaccine or antiviral medication available. There is yet no effective antidote for this virus. Patients' treatment is limited to symptomatic relief and Care that is supportive. As a result, the discovery of dengue treatments is critical. The focus of this review is on the few compounds that have been tested in dengue virus patients: Balapiravir, chloroquine, lovastatin, prednisolone, and celgosivir are some of the drugs used to treat HIV. Balapiravir was expected that the medication would also be effective against DENV because the RdRp of DENV and HCV are comparable. The lessons that these have taught us Clinical trials can be extremely useful in the development of future trials for the dengue virus's next-generation inhibitors.
Infection with the dengue virus (DENV) is the most dangerous mosquito-borne disease in the world, impacting 2.5 billion people in tropical and subtropical areas [1], [2]. DENV, a member of the Flaviviridae family, is passed from infected female Aedes mosquitoes, particularly Aedes aegypti or Aedes albopictus, to humans [3,4]. The characteristics of the four dengue virus serotypes (DENV 1-4) are similar [5, 6]. DENV can result in primary infection or secondary infection, two different forms of illnesses. Dengue fever is an acute febrile sickness brought on by an initial infection. Hemorrhagic fever (DHF) or dengue shock syndrome (DSS) are the outcomes of reinfection, which is more severe [7]. Both DHF and DSS have a high mortality rate and can result in patient death [8]. Therefore, dengue is considered a fever that poses a serious risk of death. Additionally, there is a need to create a vaccine that is effective, affordable, and secure that can combat all four DENV serotypes. Dengue envelop protein mediates the attachment of DENV to certain receptors, which starts the life cycle of the virus. During receptor-mediated endocytosis, the viral particle is merged into acidic lysosomes after engagement. The viral particle then detaches from its coating and the RNA is released into the host cell, where it controls the production of viral proteins. Tens of thousands of copies of the viral molecules are created from a single viral molecule in just a few hours following infection, causing cell damage and, in serious forms, death [9]. Three of these proteins are structural—the core protein, a surface protein, and an exterior protein—and seven of them are simplified and made. The sequence of the genes is as follows: 5′-CprM (M)-E-NS1-NS2A-NS2B-NS3-NS4A-NS4B-NS5-3′ (Figure 1) [10]. Retinoic acid inducible Gene-I, melanoma differentiation related gene-5, and Toll-like receptor-3 are all implicated in the beginning of an efficient IFN production against DENV. This is due to the enhanced transcription of both extracellular and intracellular pattern recognition receptors [11]. There isn't a vaccine preventing dengue infection at the moment. It has been difficult to produce a dengue vaccine since DENV has four different serotypes. There is a critical must to create affordable, less harmful anti- dengue medicines that can combat all dengue serotypes. 75 years ago, heterochromatin was first identified. Silence genes were discovered to be present shortly after. Using RNA interference, this heterochromatin generates short RNAs that control the alteration of proteins and DNA in heterochromatic repeats and transposable elements [12]. A quick and easy way to silence gene expression in a variety of organisms is through double-stranded RNA-mediated interference (RNAi) [13]. In addition to serving as a line of defense from entering viruses, RNAi and other silencing mechanisms are crucial in controlling how cellular genes are expressed. Researchers demonstrated that RNAi is an effective strategy for treating flavivirus infections in the host and preventing flavivirus propagation via vector [14], [15].
Fig 1: Structure of Dengue virus [16]
A cycle of communication from human to mosquito to human allows the dengue virus to multiply (Figure 2). [17] The typical time frame for developing viremia, or a state when there is a high concentration of the dengue virus in the blood, is four days after being bitten by an infectious Aedes aegypti mosquito. Viremia typically lasts five days, although it can last up to twelve days. [18] The person often has no signs of dengue on the first day of viremia. The individual experiences dengue fever characteristics five days after being bitten by an infected mosquito. These illnesses can last a week or more. A mosquito turns into a dengue vector once it has consumed the blood of a person who is afflicted with the virus. [19] The moment of viremia, when the infected person's blood contains high concentrations of the dengue virus, is when the mosquito must feed on blood. The virus is spreading throughout the mosquito's body for eight to twelve days after it has been ingested in the blood meal. The infection develops can continue to spread the dengue virus to another person while feeding after this time. [20] Does a dengue-infected mosquito simply spread the illness to the next person it bites? No, a mosquito that contracts dengue will carry the virus for the rest of its life. Healthy people can contract the dengue virus from infected mosquitoes for the remainder of their lives, which is typically a three- to four- week timeframe. [21] As their primary data of fuel, plant nectars, fruit juices, and other plant sugars are consumed by both male and female mosquitoes. So why do mosquitoes bite people? Female mosquitoes bite humans because they need blood to lay their eggs. Aedes aegypti frequently consume many blood meals prior to depositing a lot of eggs, and each female mosquito has the capacity to lay multiple batches of eggs throughout her lifespan. [22] The dengue virus can be found in the salivary glands of infected female mosquitoes. How can the virus enter a human being from the salivary glands of a mosquito? An infected female mosquito injects its saliva into the human host during a blood meal to stop the performer's blood's ability to clot and to facilitate eating. [23] The dengue virus infects the host through this infusion of saliva. Is the dengue virus only spread to people through mosquito bites? Rarely, dengue can be spread by blood transfusions from contaminated donors or organ transplants. [24] There is proof that a pregnant woman who has the dengue virus can pass it on to her fetus. Although these infrequent occurrences, mosquito bites are the primary method of transmission for dengue diseases. [25]
Fig 2: dengue virus cycle in humans and mosquito [26]
Mosquito life cycles are intricate (Figure 3). Mosquitoes modify their appearance and environments as they grow. In water-filled enclosures, female mosquitoes typically lay their eggs just above surface. Tires, buckets, birdbaths, water storage jars, and flower pots are a few examples of these vessels. [27] The mosquito eggs hatch into larvae when the containers fill with water, frequently following a downpour. The larvae are aquatic, which means that they are reliant on aquatic microbes for their food. Larvae get through the three stages of development during which they molt, or shed, their skin. The first through fourth instars refer to these pupal stages. [28] A larva passes through metamorphosis into a new form known as a pupa, the "cocoon" development for the mosquito, when it is a fully developed fourth instar. The mosquito is also waterborne at this stage of its life cycle. The fully formed adult mosquito matures and emerges from the pupa's skin after two days. The adult mosquito no longer lives in water and can fly. [29] Its environment is on land. What occurs if it doesn't rain? The Aedes aegypti mosquito has evolved so that its eggs can endure dry circumstances for a long period of time. [30] When mosquito eggs are put in a dry container, they don't hatch until the compartment is filled with water. [31] It is now very challenging to entirely eradicate mosquito populations due to this adaptability. Although infestations are more prone to occur where there are many humans in close contact with many mosquito vectors than in more remote locations, dengue can be more dangerous in densely populated regions. [32] Dengue infections are a significant public health issue in equatorial nations like Indonesia, India, Brazil, Thailand, Sri Lanka, and Myanmar that endure tropical monsoon periods. [33]
Fig 3: Aedes aegypti life cycle [34]
DENV can lead to a number of mild to serious illnesses when a mosquito bite, mainly Aedes aegypti or Aedes albopictus, is the source. [35] The United States' program to eliminate the mosquito, which came to an end in 1970, waned over time in other nations, and the mosquito started to re-infest areas where it had been previously eradicated. The geographic spread of Aedes Aegyptus was significantly greater in 2002 than it had been prior to the control and elimination, [36] which led to an increase in dengue infections. There are four distinct serotypes of DENV. Lifelong resistance to a particular DENV genotype is provided by a single initial infection. Conversely, the chance of developing a severe case of dengue increases when a person is infected with a different DENV antigen. [37]
Pathogenesis of Dengue virus
A complicated relationship seen between human immune system and viral virulence factors complicates the pathogenesis of DHF/DSS, the most severe kind of DENV infection. [38] Randomized controlled research have shown an immune system connection since there is an increased risk of DHF with secondary DENV infection and in children born to DENV- immune mothers within the first year of life. [39] These results gave rise to the concept of specific antibodies immune enhancement (ADE) of infection. The peak viremia was higher in patients with severe secondary DENV infection, validating the ADE etiology theory. In vitro antibody amplification of DENV infection in monocytes was linked to an increased risk of DHF. [40] There is a correlation between serious illnesses and elevated cytokine levels, such as interferon (IFN), tumor necrosis factor (TNF), and interleukin (IL)-10. The development of serotype-reactive low-affinity DENV-specific T cells and the engagement of CD8+ T cells have been associated with the extent of the illness [41]. After an infection with a particular serotype, an individual is immune to re-infection with the same serotype. However, infection with a different serotype can occur subsequently, as the heterologous immunity is short-lived. Based on many cohort studies, the heterotypic protective immunity gradually wanes in 1 or 2 years subsequently [42].
Dengue diagnosis requires the development of a diagnostic testing of infection. Surveillance and response and case identification are challenging owing to the fact that dengue viruses can produce asymptomatic illnesses and a range of clinical signs from a mild, nonspecific febrile sickness to a fatal hemorrhagic disease. [43] The patient's age, immunological state, genetic disorder, and the strain and serotype of the infecting virus are all significant risk factors for DHF. The virus is typically found by growing it in cell culture or by using serology to look for anti-dengue antibodies. It is possible to find and grow viral RNA and specific dengue virus antigens in vitro. [44]
The methods employed in this investigation are discussed in this chapter. It is a explanation of the study environment. The study population, the study sample, the research equipment, the technique, and the data analysis are all factors to consider.
This is a summary of prior studies on different clinical trials as a dengue virus disease treatment.
Inclusion and Exclusion Criteria
All studies on Drug candidates in clinical trials for dengue virus disease.
Data was gathered directly from prior study articles, while another portion was gathered through searching the internet for relevant information. The activities of many treatments were recorded.
All of the information gathered from prior study publications was numerically coded and imported.
There are particular difficulties in creating a dengue vaccine. The four dengue serotypes are present across the world, and exposure to one of them results in life-long protection from the same serotype of infection, [46] but merely momentary defense against the additional 3 serotypes. Additionally, dengue is distinct in that subsequent illnesses with various serotypes, the chance of getting a serious and maybe fatal illness [77]. There is few knowledge of the virus's interactions with the immune system and how specific forms of innate immunity can aggravate an illness. Consequently, a reliable and efficient dengue vaccine should be tetravalent and provide substantial and long lived protection against all 4 serotypes concurrently in to reduce the possibility of vaccination recipients becoming sensitized a really bad illness [78]. Several dengue vaccine candidates are in various stages of development. Tetravalent combinations of live attenuated viruses representing each serotype are used in the more sophisticated versions. Three of the leading possibilities have been developed using various attenuation mechanisms: [47]
Live attenuated vaccines need to be administered three times over the course of a 12-month dosing period in order to produce balanced neutralizing antibody responses to all four serotypes. As a consequence, there is a chance that an insufficient response generated by the previous vaccines will worsen illness if infection arises between the first and last vaccination. [49]
Table 1: Available Dengue vaccine
Name of vaccine |
Types of vaccine |
Manufacturer |
Dengvaxia |
live attenuated tetravalent chimeric vaccine |
Sanofi Pasteur |
TAK-003 or DENVax |
Recombinant chimeric vaccine |
Mahidol University in Bangkok |
TV-003/005 |
monovalent vaccines |
NIAID |
TDENV PIV |
inactivated vaccine |
GlaxoSmithKline (GSK) and the Walter Reed Army Institute of Research (WRAIR) |
V180 |
recombinant subunit vaccines |
Merck & Co., Inc. is an American multinational pharmaceutical company |
DNA vaccines |
monovalent DNA plasmid vaccine |
Naval Medical Research Center |
Balapiravir
A powerful blocker of the hepatitis C virus's (HCV) in vitro replication, balapiravir is a prodrug of the nucleoside analogue 4′-azidocytidine (R1479) [50]. The parent substance functions as a viral RdRp antagonist once it enters the host cell and is phosphorylated to form its 5′-triphosphate metabolite (Figure 1). Patients with chronic HCV infections have shown that balapiravir is effective [51,52]. Due to an inadequate advantage to relative risk, the clinical development of this drug for the treatment of chronic HCV was stopped [53].
It was expected that the medication would also be effective against DENV because the RdRp of DENV and HCV are comparable. With EC50 values in the range from 1.9 to 11M in human hepatoma (Huh-7) cells and 1.3 to 6.0 M in derived from human macrophages and dendritic cells, [54] balapiravir was demonstrated to suppress the replication of several DENV serotypes and strains (both lab and clinical) [55]. Peripheral blood mononuclear cells (PBMCs) were used to verify the antiviral activity, and the EC50 values ranged from 0.10 to 0.25 M [56]. Based on these objective measures, a DENV treatment trial with oral medication doses of 1500 and 3000 mg BID was developed. [57] Median plasma sensitivities as a result of this were 3.56 M and 5.85 M, correspondingly, which are 1.6- fold and 2.6-fold greater than the EC50 value discovered in macrophages [58]. The lack of potency has been attributed to a number of factors. First off, the drug might not be as effective when viremia is at its highest degree. In fact, balapiravir was 52 times less efficacious in PBMCs when added after the start of an in vitro infection [59]. The operation of balapiravir it seems to be cell form as it is generally less efficient in Huh-7 and adenocarcinomic human alveolar basal epithelial (A549) cells and to a lesser extent in human monocytic THP-1 cells than in primary cells, in addition to being less active when introduced after infection [60]. This could be because various cells have varying capacities for phosphorylating balapiravir, which produces the drug's active triphosphate metabolite.[61]
Fig 4: Mechanism of action balapiravir [62]
Chloroquine
In regions where malaria is still susceptible to its actions, chloroquine is primarily used to prevent and cure malaria. [63] Complex cases, susceptibility testing, and specific forms of malaria frequently demand for extra or alternative medicine. [64] Rheumatoid arthritis, lupus erythematosus, and amebiasis that develops beyond the intestines are other conditions that may respond to chloroquine treatment. [65] It seems safe even though it hasn't been fully studied during pregnancy. [66,67] Early in the pandemic, it was examined to treat COVID-19, but these studies were mainly stopped in the summer of 2020, and it is not advised for this use. [68] It is consumed orally. Muscle issues, appetite loss, diarrhea, and skin rashes are typical adverse effects. [69] Vision issues, muscular damage, convulsions, and low blood cell levels are serious complications. The pharmacological class 4-aminoquinoline includes chloroquine. [70] It acts as an antimalarial by inhibiting the asexual stage of the malaria parasite's life cycle inside the red blood cell. [71] It's uncertain how it functions in lupus erythematosus and rheumatoid arthritis. [73] Hans Andersag made the discovery of chloroquine in 1934. [72] It is listed as one of the Essential Medicines by the Health Organization. [73] It is accessible as a generic drug.
Celgosivir has shown a synergistic impact when combined with pegylated interferon alfa- 2b and ribavirin, both in vitro and in phase II clinical trials that last up to a year in patients with chronic HCV infection. [80] Celgosivir is ineffective as a single for the management of HCV. Celgosivir could prove to be a crucial part of standard treatment and could aid in preventing the development of drug resistance. Celgosivir's safety in humans has to be confirmed by long-term toxicity testing. [75] Celgosivir is typically well-tolerated and safe, but it doesn't appear to lower dengue fever patients' virus loads or fever incidence.[76]
Drugs targeting dengue proteins
There are a number of direct-acting antiviral medications (DAAs) that target particular dengue proteins. It is advisable for interested readers to read these excellent assessments on the most recent developments, chemical structures, and mechanisms of action of certain novel DAAs and therapeutic antibodies [91–93], which will not be covered in-depth here. Instead, we've provided thorough summaries of the development of various dengue- treatment strategies. [78]
Fig 5: Schematic view of dengue virus replication cycle. [79]
MTase inhibitors
On the newly synthesized positive-strand RNA, the NS5-MTase domain catalyzes RNA cap methylation at the N7 and 2'O sites [94]. It can also methylate the internal adenosine at the 2'-OH position of the ribose in the viral RNA genome. N7 methylation of the RNA cap is necessary for efficient translations, as MTase mutations that abolish N7 methylation are fatal for flaviviral replication [94]. The development of new substances that preferentially bind to and inhibit MTase (like "compound 10") is ongoing. Fit chemicals are currently being unmovingly isolated for additional testing [95]. Nucleoside analog (NITD008) NITD008, an adenosine analog, has been found to have antiviral effects by blocking DENV RdRP and stopping RNA chain synthesis. [96]. In vitro DENV 1-4 replications were discovered to be inhibited by NITD008. DENV-infected mice treated with NITD008 had decreased viral loads, proinflammatory cytokines, and mortality. However, this medication showed significant negative effects during preclinical toxicology studies in mice; as a result, it was not further developed for human trials [96].
Following RNA replication, helicase antagonists prevent DENV NS3 from unraveling [97]. Furthermore, the small-molecule helicase blocker ST-610 was found. This medication effectively and precisely suppressed all four DENV serotypes in vitro [98]. It successfully decreased viremia in mice while being well absorbed. Due to its poor oral bioavailability and requirement for parenteral administration, this drug's use is restricted, particularly in environments with limited resources.
A serine processor called DENV NS3 needs the cofactor NS2B to work. The production of structural and nonstructural proteins throughout proper co- and post-translational processing of the polypeptide during DENV replication is necessary for viral replication [99]. For these stages, many proteases (NS2B/NS3) synthesized by the host and virus are needed. Viral proteases are proven antiviral targets, as demonstrated by the extraordinarily powerful antagonists of HIV-1 and HCV proteases [99]. Given that the DENV 1-4 NS3 protease shares 63–74 percent of its amino acid sequence, it is possible to produce proteolytic enzymes that are efficacious against so many four DENV serotypes, however the barrier to resistance may be low. Although some potential antagonists have been identified, human clinical trials for these drugs have not yet been conducted [92].
NS4B inhibitor
Although it has no recognized enzymatic function, the transmembrane protein NS4B is essential for the production and attachment of the active viral replication complex onto ER membranes [100]. NS4B obstructs IFN-/ signaling to promote virus replication [101]. Many investigators have identified substances that interfere with NS4B to prevent DENV replication. NITD618 was one of the substances identified and demonstrated to be effective against all four DENV serotypes [102]. However, due to its poor pharmacokinetic properties and high lipophilicity, NITD618 makes in vivo experiments challenging [92]. Lycorine, a plant alkaloid that prevented the replication of WNV, YFV, and DENV 1-2, was another NS4B antagonist [103]. Another compound, SDM25N, was discovered to be effective towards DENV 2 in vitro.
Entrance/fusion blockers
E protein, which includes three cysteines, plays a major role in mediating DENV penetration into the host cell. (DI, DII, and DIII) domains [84]. in the advanced E protein, which is structured into 90 DENV particles homodimers with a covert fusion loop the dimer interaction itself. the initial stage of a virus entrance is when viral E protein binds to many cellular receptor and/or connection kinds factors (such as CD14, GRP78, laminin receptor, mannose receptor, DC-SIGN, heparin sulfate, and TAM proteins) [85]. binding is done, Viral internalization is regulated by clathrin Endenosis [85] The E protein undergoes structural changes and permutations inside the cell as a result of the acidic pH environment, exposing the fusion loop and inserting it into the endosomal membrane. Next, a membrane fusion pore forms, allowing viral RNA to enter the cytoplasm. Membrane fusion antagonists have been created and recently recommended [85]. They bind to different regions of the structural framework. Future optimisation, animal, and clinical investigations are necessary before their application [82].
DNA-based analog (NITD008)
Adenosine analog NITD008 was created, and it has been shown to have antiviral effects by inhibiting DENV RdRP and stopping the production of RNA chains [90]. Research published in vitro revealed that NITD008 decreased DENV 1-4 replication. NITD008- treated DENV-infected mice showed decreases in viral load, proinflammatory cytokines, and mortality. This medication was not subsequently researched for human trials since it also caused substantial side effects throughout preclinical toxicology investigations in mice [90].
Table 2: Available drug
Name treatments |
Mechanism |
Balapiravir |
inhibitor of the viral RdRp |
Chloroquine |
constraining the entry of (dengue) viruses |
Lovastatin |
block a variety of biological mechanisms |
Prednisolone |
Corticosteroids may reduce symptoms |
Celgosivir |
inhibits DENV1-4 clinical isolates' in vitro replication |
cromolyn, montelukast, and ketotifen |
Mast cell inhibitors |
Statins |
(HMG-CoA-reductase inhibitors) |
Drugs targeting dengue proteins |
dengue proteins inhibitor |
flaviviral |
MTase inhibitors |
DENV NS3 |
Helicase inhibitors |
thyrothricin |
Protease inhibitors |
Others |
NS4B inhibitor |
Conclusion
Over 2.5 billion people at risk of dengue illness, dengue is a challenge for global health. Dengue cases have increased dramatically over the past 50 years for causes that are still not fully understood. A severe infection can be fatal while being a short-term condition with no substantial long-term aftereffects. Dengue's pathophysiology still seems to be unknown, but it is generally agreed that the "severe disease" is caused by a reaction seen between virus and the host's over reactive immune system. There is no specific treatment for the illness; instead, palliative therapy is the only method of treatment, along with careful fluid control during the crucial stage and ongoing observation. The benefits of a dengue vaccine are enormous, yet progress in this area is delayed. There is a wide range of medicinal plant parts processing a variety of pharmacological action that were used in the treatment of several diseases [105-111].
Acknowledgments
We thank members of our groups for insightful discussions during this study.
Disclosure statement: The authors have no conflicts of interest.
Funding
This study received no specific grant from funding agencies in the public, commercial, or not-for-profit sectors.
Declaration of generative AI and AI-assisted technologies in the writing process
No AI and AI-assisted technologies used in the writing process