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Topic Review
Virus Processing
The main idea behind viral processing is to stop the viruses in a given sample from contaminating the desired product. The two most widely used methods of viral processing are viral removal and viral inactivation. The former is a method in which all viruses are simply removed from the sample completely. The latter method is one in which the viruses may remain in the final product, but in a non-infective form. These techniques are used widely in the food and blood plasma industries, as those products can be harmed by the presence of viral particles. Some of the more common viruses removed by these methods are the HIV-1 and HIV-2 viruses; hepatitis A, B, and C; and parvoviruses. The methods used in the plasma industry have been summarized (Horowitz B., Minor P., Morgenthaler J. J., Burnouf T., McIntosh R., Padilla A., Thorpe R. and van Aken W. G. Who Expert Committee on Biological Standardization. World Health Organ Tech Rep Ser. 924: 1-232, 2004.) In some cases, however, it is the virus itself that is the desired product, as is often the case with the HIV. In many cases, researchers may be trying to extract the viruses from the blood for study, not specifically for blood purification. It is also common to use these types of techniques to remove particles produced as a result of viral infection.
  • 866
  • 17 Oct 2022
Topic Review
Cancer Treatment Using Oncolytic Viruses
Oncolytic viruses can activate innate and adaptive immune mechanisms that are capable of targeting both cancer cells and viruses, it is very important to keep a balance between viral immunogenicity and anticancer immunity.
  • 865
  • 27 Jul 2021
Topic Review
HCV E1E2 Heterodimer
The envelope of HCV contains two glycoproteins, E1 and E2, that are membrane-anchored via their transmembrane domains and heterodimerize as the E1E2 complex, which in turn further multimerizes to form a trimer of heterodimers on the surface of the virion. The E1E2 complex governs viral entry and is the primary target of protective antibodies.
  • 864
  • 15 Jun 2021
Topic Review
Peptides in COVID-19 Clinical Trials
Since the beginning of the COVID-19 pandemic, there has been a strong drive and desire to find effective treatments for and protection against the disease. On the webpage ClinicalTrials.gov, a total of 6505 clinical trials currently (September 2021) investigating various aspects of COVID-19 are registered. Of these, 124 studies involving peptides were identified. These 124 were further evaluated, and 88 trials that used peptides only for routine diagnostics were excluded. The remaining 36 trials were classified into 5 different classes according to their function: immunomodulatory (5 trials), regain homeostasis (10 trials), diagnostics/biomarkers (8 trials), vaccination (9 trials), and antiviral activity (4 trials, all overlap with immunomodulatory activities). In the current review, these 36 trials are briefly described and tabularly summarised. According to the estimated finish date, 14 trials have not yet finished. All of the finished trials are yet to report their results. Seven trials were based in the USA, and Egypt, France, the UK, Turkey, and the Russian Federation conducted three trials each. This review aims to present a snapshot of the current situation of peptides in COVID-19 clinical trials and provides a template to follow up on trials of interest; it does not claim to be a complete overview.
  • 864
  • 20 Oct 2021
Topic Review
Effectiveness of COVID-19 Vaccines against Delta (B.1.617.2) Variant
The high transmissibility, mortality, and morbidity rate of the SARS-CoV-2 Delta (B.1.617.2) variant have raised concerns regarding vaccine effectiveness (VE). The short-term effectiveness of the Pfizer-BioNTech, Moderna, AstraZeneca, Bharat Biotech, and CoronaVac vaccines for the prevention of infection and the reduction in the severity of illness and hospitalizations associated with the Delta variant are supported. 
  • 863
  • 06 Jan 2022
Topic Review
Zika Virus Non-Structural Protein 1
Infection with Zika virus (ZIKV), a member of the Flavivirus genus of the Flaviviridae family, typically results in mild self-limited illness, but severe neurological disease occurs in a limited subset of patients.
  • 861
  • 15 Sep 2021
Topic Review
Aptamers in Virology - HIV
Aptamers are oligonucleotides or peptide molecules that bind specifically to a variety of targets, often inhibiting protein–protein interactions. 
  • 859
  • 13 Oct 2021
Topic Review
Evolution of H5Nx Subtypes
With the extensive divergence of the H5 hemagglutinin (HA) sequences of documented viruses, the WHO/FAO/OIE H5 Evolutionary Working Group clustered these viruses into a systematic and unified nomenclature of clade 2.3.4.4 currently known as “H5Nx” viruses. The rapid emergence and circulation of these viruses, namely, H5N2, H5N3, H5N5, H5N6, H5N8, and the regenerated H5N1, are of great concern based on their pandemic potential. 
  • 854
  • 27 Jan 2022
Topic Review
Changes in Subcellular Localization
Viruses are dependent on host factors at all parts of the infection cycle, such as translation, genome replication, encapsidation, and cell-to-cell and systemic movement. RNA viruses replicate their genome in compartments associated with the endoplasmic reticulum, chloroplasts, and mitochondria or peroxisome membranes. In contrast, DNA viruses replicate in the nucleus. Viral infection causes changes in plant gene expression and in the subcellular localization of some host proteins. These changes may support or inhibit virus accumulation and spread. Here, we review host proteins that change their subcellular localization in the presence of a plant virus. The most frequent change is the movement of host cytoplasmic proteins into the sites of virus replication through interactions with viral proteins, and the protein contributes to essential viral processes. In contrast, only a small number of studies document changes in the subcellular localization of proteins with antiviral activity. Understanding the changes in the subcellular localization of host proteins during plant virus infection provides novel insights into the mechanisms of plant–virus interactions and may help the identification of targets for designing genetic resistance to plant viruses.
  • 852
  • 22 Sep 2021
Topic Review
Porcine Circovirus Type 2
Porcine circovirus type 2 (PCV2), the causative agent of a wasting disease in weanling piglets, has periodically evolved into several new subtypes since its discovery, indicating that the efficacy of current vaccines can be improved. Although a DNA virus, the mutation rates of PCV2 resemble RNA viruses. By mutating selected serine and leucine codons to increase the probability that they would change to stop codons during replication, rapid attenuation of the vaccine construct was achieved. In a weanling piglet model, the suicidal vaccine was highly effective and safe, providing proof of concept for a novel rapid attenuation approach that is broadly applicable to newly emerging RNA and DNA viruses.
  • 851
  • 22 Sep 2021
Topic Review
Severe Acute Respiratory Syndrome Coronavirus
Severe Acute respiratory syndrome coronavirus (SARS-CoV or SARS-CoV-1) is a strain of virus that causes severe acute respiratory syndrome (SARS). It is an enveloped, positive-sense, single-stranded RNA virus which infects the epithelial cells within the lungs. The virus enters the host cell by binding to angiotensin-converting enzyme 2. It infects humans, bats, and palm civets. On 16 April 2003, following the outbreak of SARS in Asia and secondary cases elsewhere in the world, the World Health Organization (WHO) issued a press release stating that the coronavirus identified by a number of laboratories was the official cause of SARS. The Centers for Disease Control and Prevention (CDC) in the United States and National Microbiology Laboratory (NML) in Canada identified the SARS-CoV-1 genome in April 2003. Scientists at Erasmus University in Rotterdam, the Netherlands, demonstrated that the SARS coronavirus fulfilled Koch's postulates, thereby confirming it as the causative agent. In the experiments, macaques infected with the virus developed the same symptoms as human SARS victims. A similar virus was discovered in December 2019. This virus, named severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2), is the causative pathogen of the ongoing COVID-19 pandemic.
  • 850
  • 18 Oct 2022
Topic Review
HIV Infection
HIV-1 (human immunodeficiency virus type 1) is one of the most dangerous and widespread infectious viruses and causes the deaths of millions of people. The global spread of this virus, which has taken on the character of a pandemic, has made HIV a central health problem worldwide. Currently, thanks to the active development of innovative forms of antiretroviral drugs and increased access to effective means of prevention, HIV infection has become a non-fatal, and in many cases, chronic disease. Thus, the life expectancy of people living with HIV  (PLWH) has significantly increased. At the same time, in the population of PLWH, in addition to the consistenly observed higher rates of morbidity and mortality from cardiovascular diseases, various metabolic complications, and non-AIDS-related malignancies, there is a clear trend towards the spread of neurocognitive disorders.  
  • 849
  • 16 Apr 2021
Topic Review
SARS-CoV-2 Emerging Variants
Despite the slow evolutionary rate of SARS-CoV-2 relative to other RNA viruses, its massive and rapid transmission during the COVID-19 pandemic has enabled it to acquire significant genetic diversity since it first entered the human population. This led to the emergence of numerous variants, some of them recently being labeled “variants of concern” (VOC), due to their potential impact on transmission, morbidity/mortality, and the evasion of neutralization by antibodies elicited by infection, vaccination, or therapeutic application. The potential to evade neutralization is the result of diversity of the target epitopes generated by the accumulation of mutations in the spike protein. While three globally recognized VOCs (Alpha or B.1.1.7, Beta or B.1.351, and Gamma or P.1) remain sensitive to neutralization albeit at reduced levels by the sera of convalescent individuals and recipients of several anti-COVID19 vaccines, the effect of spike variability is much more evident on the neutralization capacity of monoclonal antibodies. The newly recognized VOC Delta or lineage B.1.617.2, as well as locally accepted VOCs (Epsilon or B.1.427/29-US and B1.1.7 with the E484K-UK) are indicating the necessity of close monitoring of new variants on a global level. The VOCs characteristics, their mutational patterns, and the role mutations play in immune evasion are summarized in this review. 
  • 849
  • 12 Jul 2021
Topic Review
Viral Vectors
Viral vectors can generate high levels of recombinant protein expression providing the basis for modern vaccine development. A large number of different viral vector expression systems have been utilized for targeting viral surface proteins and tumor-associated antigens.
  • 848
  • 23 Apr 2021
Topic Review
First Alternavirus Identified in Fusarium oxysporum
A novel mycovirus named Fusarium oxysporum alternavirus 1(FoAV1) was identified as infecting Fusarium oxysporum strain BH19, which was isolated from a fusarium wilt diseased stem of Lilium brownii. The genome of FoAV1 contains four double-stranded RNA (dsRNA) segments (dsRNA1, dsRNA 2, dsRNA 3 and dsRNA 4, with lengths of 3.3, 2.6, 2.3 and 1.8 kbp, respectively). Additionally, dsRNA1 encodes RNA-dependent RNA polymerase (RdRp), and dsRNA2- dsRNA3- and dsRNA4-encoded hypothetical proteins (ORF2, ORF3 and ORF4), respectively. A homology BLAST search, along with multiple alignments based on RdRp, ORF2 and ORF3 sequences, identified FoAV1 as a novel member of the proposed family "Alternaviridae". Evolutionary relation analyses indicated that FoAV1 may be related to alternaviruses, thus dividing the family "Alternavirida" members into four clades. In addition, we determined that dsRNA4 was dispensable for replication and may be a satellite-like RNA of FoAV1—and could perhaps play a role in the evolution of alternaviruses. Our results provided evidence for potential genera establishment within the proposed family "Alternaviridae". Additionally, FoAV1 exhibited biological control of Fusarium wilt.
  • 847
  • 23 Nov 2021
Topic Review Peer Reviewed
Extracellular Vesicles and Immunomodulation in Mosquitoes and Ticks
Extracellular vesicles are small blebs that are secreted by cells, which are lipid-rich and contain proteomic and genomic material (including small RNAs, mRNA, and plasmid DNA). These materials are delivered into recipient cells leading to a phenotypic change. Recent studies have demonstrated the secretion of extracellular vesicles by mosquito and tick cells, as well as tick salivary glands. Further, these studies suggest vesicles play a role in the transmission of vector-borne pathogens, including viruses and bacteria, and are involved in the manipulation of wound healing and immune responses. Both of these processes are key in the host response to hematophagous arthropods’ feeding. The role of mosquito and tick EVs in the modulation of immune responses and pathogen transmission is discussed in this entry.
  • 845
  • 24 Apr 2022
Topic Review
Clinical Management of Malaria and HIV Co-Infection
Malaria and HIV are geographically in the tropics and subtropics of the world, including sub-Saharan Africa. Understanding the overlapping effect of both infections, especially among pregnant women, is crucial in managing pregnant women during antenatal care visits, and postpartum babies. It was realized that the prevalence of malaria among HIV-positive pregnant women ranges between 31–61%, while for non-HIV infected pregnant women the prevalence still stands between 10 and 36%. Co-infection is between 0.52 and 56.3%.
  • 843
  • 23 Apr 2023
Topic Review
Satellite Subgenomic Particles Key Regulators
Historically, adeno-associated virus (AAV)-defective interfering particles (DI) were known as abnormal virions arising from natural replication and encapsidation errors. In this study, from analyzing the genome configurations of DI particles, a major category of DI particles is revealed, which contains a double stranded DNA genome in a “snapback” configuration. Such molecules may enhance the capsid protein expression and modulate rep expression. The subgenomic particles play an important role in the life cycle wild type AAV.
  • 842
  • 05 Jul 2021
Topic Review
Influenza A (H7N9) Human Adaptation
Avian influenza virus A (H7N9), after circulating in avian hosts for decades, was identified as a human pathogen in 2013. Herein, we focus on the quantification of the virus diversity and the identification of amino acid substitutions that are possibly essential for human adaptation.
  • 841
  • 14 Dec 2021
Topic Review
Diagnostic Utility and Vaccine Development of SARS-CoV-2 Antibodies
Antibodies (Abs) are important immune mediators and powerful diagnostic markers in a wide range of infectious diseases. Understanding the humoral immunity or the development of effective antibodies against SARS-CoV-2 is a prerequisite for limiting disease burden in the community and aids in the development of new diagnostic, therapeutic, and vaccination options. Antibody testing showed the potential in adding important diagnostic value to the routine diagnosis and clinical management of COVID-19. They could also play a critical role in COVID-19 surveillance, allowing for a better understanding of the full scope of the disease. The development of several vaccines and the success of passive immunotherapy suggest that anti-SARS-CoV-2 antibodies have the potential to be used in the treatment and prevention of SARS-CoV-2 infection.
  • 840
  • 21 Nov 2022
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