Viral loadViral load, also known as viral burden, is a numerical expression of the quantity of virus in a given volume of fluid, including biological and environmental specimens. It is not to be confused with viral titre or viral titer, which depends on the assay. When an assay for measuring the infective virus particle is done (Plaque assay, Focus assay), viral titre often refers to the concentration of infectious viral particles, which is different from the total viral particles. Viral load is measured using body fluids Sputum and blood plasma.
Genetic variationGenetic variation is the difference in DNA among individuals or the differences between populations among the same species. The multiple sources of genetic variation include mutation and genetic recombination. Mutations are the ultimate sources of genetic variation, but other mechanisms, such as genetic drift, contribute to it, as well. Genetic variation can be identified at many levels. Identifying genetic variation is possible from observations of phenotypic variation in either quantitative traits (traits that vary continuously and are coded for by many genes (e.
HIVThe human immunodeficiency viruses (HIV) are two species of Lentivirus (a subgroup of retrovirus) that infect humans. Over time, they cause acquired immunodeficiency syndrome (AIDS), a condition in which progressive failure of the immune system allows life-threatening opportunistic infections and cancers to thrive. Without treatment, average survival time after infection with HIV is estimated to be 9 to 11 years, depending on the HIV subtype.
InfectionAn infection is the invasion of tissues by pathogens, their multiplication, and the reaction of host tissues to the infectious agent and the toxins they produce. An infectious disease, also known as a transmissible disease or communicable disease, is an illness resulting from an infection. Infections can be caused by a wide range of pathogens, most prominently bacteria and viruses. Hosts can fight infections using their immune systems. Mammalian hosts react to infections with an innate response, often involving inflammation, followed by an adaptive response.
Genetic diversityGenetic diversity is the total number of genetic characteristics in the genetic makeup of a species, it ranges widely from the number of species to differences within species and can be attributed to the span of survival for a species. It is distinguished from genetic variability, which describes the tendency of genetic characteristics to vary. Genetic diversity serves as a way for populations to adapt to changing environments. With more variation, it is more likely that some individuals in a population will possess variations of alleles that are suited for the environment.
MutationIn biology, a mutation is an alteration in the nucleic acid sequence of the genome of an organism, virus, or extrachromosomal DNA. Viral genomes contain either DNA or RNA. Mutations result from errors during DNA or viral replication, mitosis, or meiosis or other types of damage to DNA (such as pyrimidine dimers caused by exposure to ultraviolet radiation), which then may undergo error-prone repair (especially microhomology-mediated end joining), cause an error during other forms of repair, or cause an error during replication (translesion synthesis).
HIV/AIDSHuman immunodeficiency virus infection and acquired immunodeficiency syndrome (HIV/AIDS) is a spectrum of conditions caused by infection with the human immunodeficiency virus (HIV), a retrovirus. Following initial infection an individual may not notice any symptoms, or may experience a brief period of influenza-like illness. Typically, this is followed by a prolonged incubation period with no symptoms.
Diagnosis of HIV/AIDSHIV tests are used to detect the presence of the human immunodeficiency virus (HIV), the virus that causes acquired immunodeficiency syndrome (AIDS), in serum, saliva, or urine. Such tests may detect antibodies, antigens, or RNA. AIDS-defining clinical condition AIDS is diagnosed separately from HIV. The window period is the time from infection until a test can detect any change. The average window period with HIV-1 antibody tests is 25 days for subtype B.
Viral envelopeA viral envelope is the outermost layer of many types of viruses. It protects the genetic material in their life cycle when traveling between host cells. Not all viruses have envelopes. A viral envelope protein or E protein is a protein in the envelope, which may be acquired by the capsid from an infected host cell. Numerous human pathogenic viruses in circulation are encased in lipid bilayers, and they infect their target cells by causing the viral envelope and cell membrane to fuse.
Genetic recombinationGenetic recombination (also known as genetic reshuffling) is the exchange of genetic material between different organisms which leads to production of offspring with combinations of traits that differ from those found in either parent. In eukaryotes, genetic recombination during meiosis can lead to a novel set of genetic information that can be further passed on from parents to offspring.
Human genetic variationHuman genetic variation is the genetic differences in and among populations. There may be multiple variants of any given gene in the human population (alleles), a situation called polymorphism. No two humans are genetically identical. Even monozygotic twins (who develop from one zygote) have infrequent genetic differences due to mutations occurring during development and gene copy-number variation. Differences between individuals, even closely related individuals, are the key to techniques such as genetic fingerprinting.
Viral marketingViral marketing is a business strategy that uses existing social networks to promote a product mainly on various social media platforms. Its name refers to how consumers spread information about a product with other people, much in the same way that a virus spreads from one person to another. It can be delivered by word of mouth, or enhanced by the network effects of the Internet and mobile networks. The concept is often misused or misunderstood, as people apply it to any successful enough story without taking into account the word "viral".
Host (biology)In biology and medicine, a host is a larger organism that harbours a smaller organism; whether a parasitic, a mutualistic, or a commensalist guest (symbiont). The guest is typically provided with nourishment and shelter. Examples include animals playing host to parasitic worms (e.g. nematodes), cells harbouring pathogenic (disease-causing) viruses, or a bean plant hosting mutualistic (helpful) nitrogen-fixing bacteria. More specifically in botany, a host plant supplies food resources to micropredators, which have an evolutionarily stable relationship with their hosts similar to ectoparasitism.
Viral entryViral entry is the earliest stage of infection in the viral life cycle, as the virus comes into contact with the host cell and introduces viral material into the cell. The major steps involved in viral entry are shown below. Despite the variation among viruses, there are several shared generalities concerning viral entry. How a virus enters a cell is different depending on the type of virus it is. A virus with a nonenveloped capsid enters the cell by attaching to the attachment factor located on a host cell.
GenomeIn the fields of molecular biology and genetics, a genome is all the genetic information of an organism. It consists of nucleotide sequences of DNA (or RNA in RNA viruses). The nuclear genome includes protein-coding genes and non-coding genes, other functional regions of the genome such as regulatory sequences (see non-coding DNA), and often a substantial fraction of junk DNA with no evident function. Almost all eukaryotes have mitochondria and a small mitochondrial genome.
VirologyVirology is the scientific study of biological viruses. It is a subfield of microbiology that focuses on their detection, structure, classification and evolution, their methods of infection and exploitation of host cells for reproduction, their interaction with host organism physiology and immunity, the diseases they cause, the techniques to isolate and culture them, and their use in research and therapy.
Antiviral drugAntiviral drugs are a class of medication used for treating viral infections. Most antivirals target specific viruses, while a broad-spectrum antiviral is effective against a wide range of viruses. Antiviral drugs are one class of antimicrobials, a larger group which also includes antibiotic (also termed antibacterial), antifungal and antiparasitic drugs, or antiviral drugs based on monoclonal antibodies. Most antivirals are considered relatively harmless to the host, and therefore can be used to treat infections.
Copy number variationCopy number variation (CNV) is a phenomenon in which sections of the genome are repeated and the number of repeats in the genome varies between individuals. Copy number variation is a type of structural variation: specifically, it is a type of duplication or deletion event that affects a considerable number of base pairs. Approximately two-thirds of the entire human genome may be composed of repeats and 4.8–9.5% of the human genome can be classified as copy number variations.
SARS-CoV-2Severe acute respiratory syndrome coronavirus 2 (SARS‐CoV‐2) is a strain of coronavirus that causes COVID-19, the respiratory illness responsible for the COVID-19 pandemic. The virus previously had the provisional name 2019 novel coronavirus (2019-nCoV), and has also been called human coronavirus 2019 (HCoV-19 or hCoV-19). First identified in the city of Wuhan, Hubei, China, the World Health Organization designated the outbreak a public health emergency of international concern from January 30, 2020, to May 5, 2023.
SARS-CoV-2 Omicron variantOmicron (B.1.1.529) is a variant of SARS-CoV-2 first reported to the World Health Organization (WHO) by the Network for Genomics Surveillance in South Africa on 24 November 2021. It was first detected in Botswana and has spread to become the predominant variant in circulation around the world. Following the original B.1.1.529 variant, several subvariants of Omicron have emerged including: BA.1, BA.2, BA.3, BA.4, and BA.5. Since October 2022, two subvariants of BA.5 called BQ.1 and BQ.1.1 have emerged.
