Instruct: Given a question, retrieve passages that can help answer the question.
Query: How many species of Lentivirus are there?
Five serogroups of lentiviruses are recognized, reflecting the vertebrate hosts with which they are associated (primates, sheep and goats, horses, domestic cats, and cattle).[3] The primate lentiviruses are distinguished by the use of CD4 protein as a receptor and the absence of dUTPase.[4] Some groups have cross-reactive gag antigens (e.g., the ovine, caprine, and feline lentiviruses). Antibodies to gag antigens in lions and other large felines indicate the existence of another yet to be identified virus related to feline lentivirus and the ovine/caprine lentiviruses.
EVEs are a rare source of retrospective information about ancient viruses. Many are derived from germline integration events that occurred millions of years ago, and can be viewed as viral fossils. Such ancient EVEs are an important component of paleovirological studies that address the long-term evolution of viruses.
Identification of orthologous EVE insertions enables the calibration of long-term evolutionary timelines for viruses, based on the estimated time since divergence of the ortholog-containing host species groups. This approach has provided minimum ages ranging from 30-93 million years for the "Parvoviridae", "Filoviridae", "Bornaviridae" and "Circoviridae" families of viruses, and 12 million years for the Lentivirus genus of the "Retroviridae" family. EVEs also facilitate the use of molecular clock-based approaches to obtain calibrations of viral evolution in deep time.
Species concepts are the subject of debate in the field of molecular ecology. Since the beginning of taxonomy, scientists have wanted to standardize and perfect the way species are defined. There are many species concepts that dictate how ecologists determine a good species. The most commonly used concept is the biological species concept which defines a species as groups of actually or potentially interbreeding natural populations, which are reproductively isolated from other such groups (Mayr, 1942). This concept is not always useful, particularly when it comes to hybrids. Other species concepts include phylogenetic species concept which describes a species as the smallest identifiable monophyletic group of organisms within which there is a parental pattern of ancestry and descent. This concept defines species on the identifiable. It would also suggest that until two identifiable groups actually produce offspring, they remain separate species. In 1999, John Avise and Glenn Johns suggested a standardized method for defining species based on past speciation and measuring biological classifications as time dependent. Their method used temporal banding to make genus, family and order based on how many tens of millions of years ago the speciation event that resulted in each species took place.
The niche concept was popularized by the zoologist G. Evelyn Hutchinson in 1957. Hutchinson inquired into the question of why there are so many types of organisms in any one habitat. His work inspired many others to develop models to explain how many and how similar coexisting species could be within a given community, and led to the concepts of 'niche breadth' (the variety of resources or habitats used by a given species), 'niche partitioning' (resource differentiation by coexisting species), and 'niche overlap' (overlap of resource use by different species).
Studies of correcting Wiskott–Aldrich syndrome with gene therapy using a lentivirus have begun.
Proof-of-principle for successful hematopoietic stem cell gene therapy has been provided for patients with Wiskott–Aldrich syndrome.
Currently, many investigators continue to develop optimized gene therapy vectors. In July 2013 the Italian San Raffaele Telethon Institute for Gene Therapy (HSR-TIGET) reported that three children with Wiskott–Aldrich syndrome showed significant improvement 20–30 months after being treated with a genetically modified lentivirus. In April 2015 results from a follow-up British and French trial where six children with Wiskott–Aldrich syndrome were treated with gene therapy were described as promising. Median follow-up time was 27 months.
Lentivirus (lente-, Latin for "slow") is a genus of retroviruses that cause chronic and deadly diseases characterized by long incubation periods, in the human and other mammalian species.[1] The best known lentivirus is the Human Immunodeficiency Virus (HIV), which causes AIDS. Lentiviruses are also hosted in apes, cows, goats, horses, cats, and sheep.[1] Recently, lentiviruses have been found in monkeys, lemurs, Malayan flying lemur (neither a true lemur nor a primate), rabbits, and ferrets. Lentiviruses and their hosts have worldwide distribution. Lentiviruses can integrate a significant amount of viral cDNA into the DNA of the host cell and can efficiently infect nondividing cells, so they are one of the most efficient methods of gene delivery.[2] Lentiviruses can become endogenous (ERV), integrating their genome into the host germline genome, so that the virus is henceforth inherited by the host's descendants.
Visna virus (also known as visna-maedi virus, maedi-visna virus and ovine lentivirus) from the genus Lentivirus and subfamily Orthoretrovirinae, is a "prototype" retrovirus that causes encephalitis and chronic pneumonitis in sheep. It is known as visna when found in the brain, and maedi when infecting the lungs. Lifelong, persistent infections in sheep occur in the lungs, lymph nodes, spleen, joints, central nervous system, and mammary glands; The condition is sometimes known as "ovine progressive pneumonia" (OPP), particularly in the United States, or "Montana sheep disease". White blood cells of the monocyte/macrophage lineage are the main target of visna virus.
Serological Relationships: Antigen determinants are type-specific and group-specific. Antigen determinants that possess type-specific reactivity are found on the envelope. Antigen determinants that possess type-specific reactivity and are involved in antibody mediated neutralization are found on the glycoproteins. Cross-reactivity has been found among some species of the same serotype, but not between members of different genera. Classification of members of this taxon is infrequently based on their antigenic properties.
Lentivirus is primarily a research tool used to introduce a gene product into in vitro systems or animal models. Large-scale collaborative efforts are underway to use lentiviruses to block the expression of a specific gene using RNA interference technology in high-throughput formats.[7] The expression of short-hairpin RNA (shRNA) reduces the expression of a specific gene, thus allowing researchers to examine the necessity and effects of a given gene in a model system. These studies can be a precursor to the development of novel drugs which aim to block a gene-product to treat diseases. Conversely, lentivirus are also used to stably over-express certain genes, thus allowing researchers to examine the effect of increased gene expression in a model system.
The measure of ongoing species loss is made more complex by the fact that most of the Earth's species have not been described or evaluated. Estimates vary greatly on how many species actually exist (estimated range: 3,600,000-111,700,000) to how many have received a species binomial (estimated range: 1.5-8 million). Less than 1% of all species that have been described beyond simply noting its existence. From these figures, the IUCN reports that 23% of vertebrates, 5% of invertebrates and 70% of plants that have been evaluated are designated as endangered or threatened. Better knowledge is being constructed by The Plant List for actual numbers of species.
In a Phase I clinical trial of three patients, two showed no improvement and one of them had some improvements. The study concluded further investigation is warranted for the use of the procedure to treat Leber's congenital amaurosis. Other early trials have been used to explore the treatments potential, including for therapeutic use of recombinant adeno-associated virus (rAAV) vectors. Many other possible viral vectors remain options for the treatment of various genetic disorders in the retina that lead to blindness. Retinal gene therapy using lentivirus vectors may be a way to treat a wider range of genetic disorders in the retina because of the various properties of the lentivirus that make it an attractive alternative to rAAV vectors.
For the purposes of gene therapy, one might either want to limit or expand the range of cells susceptible to transduction by a gene therapy vector. To this end, many vectors have been developed in which the endogenous viral envelope proteins have been replaced by either envelope proteins from other viruses, or by chimeric proteins. Such chimera would consist of those parts of the viral protein necessary for incorporation into the virion as well as sequences meant to interact with specific host cell proteins. Viruses in which the envelope proteins have been replaced as described are referred to as pseudotyped viruses. For example, the most popular retroviral vector for use in gene therapy trials has been the lentivirus Simian immunodeficiency virus coated with the envelope proteins, G-protein, from Vesicular stomatitis virus. This vector is referred to as VSV G-pseudotyped lentivirus, and infects an almost universal set of cells. This tropism is characteristic of the VSV G-protein with which this vector is coated. Many attempts have been made to limit the tropism of viral vectors to one or a few host cell populations. This advance would allow for the systemic administration of a relatively small amount of vector. The potential for off-target cell modification would be limited, and many concerns from the medical community would be alleviated. Most attempts to limit tropism have used chimeric envelope proteins bearing antibody fragments. These vectors show great promise for the development of "magic bullet" gene therapies.
Classed as having class C morphology
In the early 1940s Alexander Steven Corbet spent 2 years in Malaya trapping butterflies. He kept track of how many species he observed, and how many members of each species were captured. For example, he captured only 2 members of 74 different species. When he returned to the United Kingdom, he approached statistician Ronald Fisher, and asked how many new species of butterflies he could expect to catch if he went trapping for another two years. In essence, Corbet was asking how many species he observed zero times.Fisher responded with a simple estimation: for an additional 2 years of trapping, Corbet could expect to capture 75 new species. He did this using a simple summation (data provided by Orlitsky in Table 1 below in the Example section):formula_7Here, formula_8 corresponds to the number of individual species which were observed formula_9 times. Fisher's sum was later confirmed by Good–Toulmin.
A scientist claims she was infected by a genetically modified virus while working for Pfizer. In her federal lawsuit she says she has been intermittently paralyzed by the Pfizer-designed virus. "McClain, of Deep River, suspects she was inadvertently exposed, through work by a former Pfizer colleague in 2002 or 2003, to an engineered form of the lentivirus, a virus similar to the one that can lead to acquired immune deficiency syndrome, also known as AIDS." The court found that McClain failed to demonstrate that her illness was caused by exposure to the lentivirus, but also that Pfizer violated whistleblower laws.
Nef Vpr Vif Vpu/Vpx p6
Puma lentivirus (PLV) is a retrovirus. A study in 2003 indicated that domestic cats infected with puma lentivirus (PLV) or lion lentivirus (LLV) began producing anti-FIV immune responses.
In 2008, discovery of an endogenous lentivirus in a prosimian (proto-monkey) primate, the gray mouse lemur native to Madagascar, pushed the origin of SIV-like lentivirus infections in primates back to at least 14 Ma, the last time there was intermingling of mammals between the island of Madagascar and the African mainland, if the infection is attributed to horizontal transmission between homologous hosts. If the virus and host were coevolved, rather
than acquired, that potentially pushes the date of the endogenous event back to approx. 85 Ma, the split between the lemur-like and monkey-like primate lineages. That date barely antedates the emergence of the primates 87.7 Ma.
Feline immunodeficiency virus (FIV) is a lentivirus that affects cats worldwide. From 2.5% up to 4.4% of cats worldwide are infected with FIV. FIV differs taxonomically from two other feline retroviruses, feline leukemia virus (FeLV) and feline foamy virus (FFV), and is more closely related to human immunodeficiency virus (HIV). Within FIV, five subtypes have been identified based on nucleotide sequence differences coding for the viral envelope (env) or polymerase (pol). FIV is the only non-primate lentivirus to cause an AIDS-like syndrome, but FIV is not typically fatal for cats, as they can live relatively healthily as carriers and transmitters of the disease for many years. A vaccine is available although its efficacy remains uncertain. Cats will test positive for FIV antibodies after vaccination.
Generally, genetic modification entails manipulation of DNA. The process is known as cisgenesis when a gene is transferred between organisms that could be conventionally bred, or transgenesis when a gene from one species is added to a different species. Gene transfer into the genome of the desired organism, as for fish in this case, requires a vector like a lentivirus or mechanical/physical insertion of the altered genes into the nucleus of the host by means of a micro syringe or a gene gun.
A scientist claims she was infected by a genetically modified virus while working for Pfizer. In her federal lawsuit she says she has been intermittently paralyzed by the Pfizer-designed virus. "McClain, of Deep River, suspects she was inadvertently exposed, through work by a former Pfizer colleague in 2002 or 2003, to an engineered form of the lentivirus, a virus similar to the one that can lead to acquired immune deficiency syndrome, or AIDS." The court found that McClain failed to demonstrate that her illness was caused by exposure to the lentivirus, but also that Pfizer violated whistleblower laws.
Functional redundancy refers to the phenomenon that species in the same ecosystem fill similar roles, which results in a sort of "insurance" in the ecosystem. Redundant species can easily do the job of a similar species from the same functional niche. This is possible because similar species have adapted to fill the same niche overtime. Functional redundancy varies across ecosystems and can vary from year to year depending on multiple factors including habitat availability, overall species diversity, competition among species for resources, and anthropogenic influence. This variation can lead to a fluctuation in overall ecosystem production. It is not always known how many species occupy a functional niche, and how much, if any, redundancy is occurring in each niche in an ecosystem. It is hypothesized that each important functional niche is filled by multiple species. Similar to functional diversity, there is no one clear method for calculating functional redundancy accurately, which can be problematic. One method is to account for the number of species occupying a functional niche, as well as the abundance of each species. This can indicate how many total individuals in an ecosystem are performing one function.
There is therefore considerable disagreement on how many species exist, with as many as 100 names being listed. Current studies tend to agree that there are between 16 and 23 species.
Lentivirus are a family of viruses that are responsible for notable diseases like HIV. The lentivirus is unique in that it has been the basis of research using viruses in gene therapy. To be effective in gene therapy, there must be insertion, alteration and/or removal of host cell genes. To do this scientists use the lentivirus' mechanisms of infection to achieve a desired outcome to gene therapy.
Structural proteins listed by size: