In epidemiology , infectivity refers to the ability of a pathogen to establish an infection. More specifically, infectivity is a pathogen s capacity for horizontal transmission that is, how frequently it spreads among host biology host s that are not in a parent child relationship. It is closely related to the concept of incidence epidemiology incidence , which is the measure of infectivity in a population. Infectivity has been shown to correlation positively correlate with virulence . This means that as a pathogen s ability to infect a greater number of hosts increases, so does the level of harm it brings to the host. ref cite journal title An empirical study of the evolution of virulence under both horizontal and vertical transmission last1 Stewart first1 AD last2 Logsdon first2 JM last3 Kelley first3 SE journal Evolution year 2005 month April volume 59 issue 4 pages 730 739 doi 10.1554 03 330 pmid 15926685 ref A pathogen s infectivity is subtly but importantly different from its transmissibility epidemiology transmissibility , which refers to a pathogen s capacity to pass from parent to child. References reflist External links http www.medterms.com script main art.asp?articlekey 24094 Def Category Epidemiology Category Article Feedback 5 med stub de Infektiosit t eo Infektebleco es Infectividad it Infettivit nl Besmettelijkheid pl Zaka no ... more details
Image HIV genome.png thumb 402px HIV genome Viral infectivity factor , or Vif, is a protein found in HIV and other retrovirus es. Its role is to disrupt the antiviral activity of the human enzyme APOBEC See also APOBEC3G by targeting it for ubiquitination and cellular degradation. APOBEC is a cytidine deaminase enzyme that mutates viral nucleic acids. File Crystal Structure of the HIV Vif BC box in Complex with Human ElonginB and ElonginC.png 400px thumb Ribbon representation of Crystal Structure of the HIV Vif BC box in Complex with Human ElonginB and ElonginC ref cite journal last Stanley first BJ coauthors Ehrlich, E.S., Short, L., Yu, Y., Xiao, Z., Yu, X. F., Xiong, Y. title Structural insight into the human immunodeficiency virus Vif SOCS box and its role in human E3 ubiquitin ligase assembly. journal J.Virol. date 18 year 2008 month Jun volume 82 pages 8656 63 doi 10.1128 JVI.00767 08 pmid 18562529 pmc 2519636 rendered with http pymol.sourceforge.net PyMOL ref Vif is a 23 kilodalton protein that is essential for viral replication. Vif inhibits the cellular protein, APOBEC3G , from entering the virion during budding from a host cell by targeting it for proteasomal degradation. Vif hijacks the cellular Cullin5 E3 ubiquitin ligase, which is composed of ElonginB, ElonginC, Cullin5, and Rbx2, Crystal Structure of the HIV Vif BC box in Complex with Human ElonginB and ElonginC is solved and shown here ref cite journal last Stanley first BJ coauthors Ehrlich, E.S., Short, L., Yu, Y., Xiao, Z., Yu, X. F., Xiong, Y. title Structural insight into the human immunodeficiency virus Vif SOCS box and its role in human E3 ubiquitin ligase assembly. journal J.Virol. date 18 year 2008 month Jun volume 82 pages 8656 63 doi 10.1128 JVI.00767 08 pmid 18562529 pmc 2519636 ref in order to target ... title The dimerization domain of HIV 1 viral infectivity factor Vif is required to block APOBEC3G ... External links MeshName vif Protein Viral proteins DEFAULTSORT Viral Infectivity Factor Category ... more details
A microbicide is any compound or substance whose purpose is to reduce the infectivity of microbes, such as virus es or bacterium bacteria . One example is Wood Tar ref cite journal last Paulus first W title Microbicides for the protection of materials yesterday, today and tomorrow journal Biodeterioration and Biodegradation volume 8 year 1991 ref . See also Antibiotics Bactericide Disinfectant Fungicide Microbicides for sexually transmitted diseases References Reflist Microbicides for sexually transmitted diseases Category Antimicrobials Category Microbicides antiinfective drug stub de Mikrobizid ... more details
Human influenza hemagglutinin HA is a surface glycoprotein required for the infectivity of the human virus. The HA tag is derived from the HA molecule corresponding to amino acids 98 106 has been extensively used as a general epitope tag in expression vectors. Many recombinant proteins have been engineered to express the HA tag, which does not appear to interfere with the bioactivity or the biodistribution of the recombinant protein. This tag facilitates the detection, isolation, and purification of the proteins. Propriety The actual HA tag is as follows 5 TAC CCA TAC GAT GTT CCA GAT TAC GCT 3 The amino acid sequence YPYDVPDYA Category Influenza Category Viral structural proteins ... more details
Saglin is a protein produced by the salivary glands of mosquitoes . It is thought that this protein allows the malarial sporozoite to bind to the salivary glands, allowing invasion ref name Oku Okulate et al. 2007 Identification and molecular characterization of a novel protein Saglin as a target of monoclonal antibodies affecting salivary gland infectivity of Plasmodium sporozoites ref . It is currently under investigation as a potential drug target to help control transmission of the disease by controlling transmission in the Vector epidemiology vector ref name mykle The Saglin Project http bioquest.org oakwood2008 2008 08 this is the saglin project ref . References reflist Category Proteins ... more details
A peplomer is a glycoprotein spike on a virus viral capsid or viral envelope . ref cite book title Saunders Comprehensive Veterinary Dictionary edition 3rd year 2007 publisher Elsevier Elsevier, Inc as cited in cite web title peplomer work The Free Dictionary publisher Farlex accessdate 30 Mar 2011 url http medical dictionary.thefreedictionary.com peplomer year 2011 ref These protrusions will only bind to certain receptor biochemistry receptors on the host Cell biology cell they are essential for both host biology host specificity and viral infectivity . The term peplomer is typically used to refer to a grouping of heterologous proteins on the virus surface that function together. The tail fibers of some bacteriophages , especially the Enterobacteria phage T4 T4 like phages, are modified peplomers. See also Virus Glycoprotein Receptor biochemistry T4 phage Viral entry Viral life cycle References reflist Category Virology Category Microbiology Virus stub de Peplomer it Peplomero pt Pepl mero ... more details
Unreferenced date March 2007 Orphan date June 2011 Host factor is a medicine medical term referring to the traits of an individual person or animal that affect susceptibility to disease , especially in comparison to other individuals. The term arose in the context of infectious disease research, in contrast to organism factors , such as the virulence and infectivity of a microbe. Host factors that may vary in a population and affect disease susceptibility can be innate or acquired. Some examples general health psychological characteristics and attitude nutrition al state social ties previous exposure to the organism or related antigen s haplotype or other specific genetic differences of immune function substance abuse Race classification of human beings race The term is now used in oncology and many other medical contexts related to individual differences of disease vulnerability. See also Vulnerability index Epidemiology Immunology DEFAULTSORT Host Factor Category Diseases and disorders med stub ... more details
Phenol soluble modulins PSM are a family of protein toxin s that are soluble in phenol s, that are produced by Methicillin resistant Staphylococcus aureus CA MRSA , and which are thought to be a possible cause of severe infections. ref name Graves Cite doi 10.1007 s00109 009 0573 x ref Non methicillin resistant bacteria were not found to produce these toxins. Although PSM toxins are produced in all methicillin resistant Staphylococcus aureus strains, the more virulent CA MRSA strains are typically associated with higher production. Genetic analysis demonstrated that the PSM alpha protein, product of the psm alpha gene cluster , was associated with enhanced virulence and enhanced destruction of white blood cell s, presumably the key to the higher infectivity. However, expression of the psm alpha genes appeared to vary, dependent upon unknown factors specific to each particular infection. ref name Wang Cite doi 10.1038 nm1656 ref References references Category Staphylococcaceae Category Bacterial toxins Category Occupational safety and health ... more details
Orphan date October 2009 Replikins are a group of peptides , whose increase in concentration in virus or other organism proteins is associated with rapid replication. It is often measured in number of replikins per 100 amino acids. This particular group of peptides have been found to play a significant role in predicting both infectivity and lethality of various viral strains. In particular, this group allowed the prediction of the A H1N1 pandemic almost one year before onset. ref http www.sciencedaily.com releases 2009 06 090602161944.htm Efforts To Quickly Develop Swine Flu Vaccine ref A method for identifying replikins was patented by Samuel and Elenore S. Bogoch in 2001. ref http www.freshpatents.com Replikin peptides and antibodies therefore dt20090528ptan20090137778.php Replikin peptides and antibodies therefore ref The peptide group was first identified by a proprietary company called Replikins, who have trademarked the name Replikin Count . The patent application in references refers to patent class 530324000 also see http www.freshpatents.com dt20090115ptan20090017052.php References Reflist External links http www.replikins.com Replikins web site See also 2009 flu pandemic Category Peptides Biochem stub ... more details
The following is a list of types of poison by intended use Algicide a substance used for killing and preventing the growth of algae Avicide any substance which can be used to kill bird s Biocide a chemical substance capable of killing life living organisms , usually in a selective way Fungicide a chemical compound or biological organism used to kill or inhibit fungi or fungal spores Microbicide any compound or substance whose purpose is to reduce the infection infectivity of microbe s Germicide a disinfectant Bactericide a substance that kills bacteria Viricide a chemical agent which kills viruses outside the body Herbicide a substance used to kill unwanted plants wikt parasiticide Parasiticide any substance used to kill parasite s Pesticide a substance or mixture of substances used to kill a pest organism pest Acaricide pesticide s that kill mite s Insecticide a pesticide used against insect s Molluscicide pesticide s against molluscs Nematocide a type of chemical pesticide used to kill parasitic nematode s roundworms Rodenticide a category of pest control chemicals intended to kill rodent s Spermicide a substance that kills sperm Category Toxicology Category Poisons ... more details
Unreferenced date April 2010 Introduction Bacteriophage P2 is a temperate phage that infects E. coli . It is a tailed virus with a contractile sheath and is thus classified in the family Myoviridae and the order Caudovirales , tailed viruses. Phage P2 has a double stranded DNA genome packaged in an icosahedral capsid with a diameter of 60 nm that is connected to a 135 nm long tail. The tail ends in a baseplate which is the control hub for phage infectivity. The baseplate includes 6 tail fibers which initially bind to receptors on the bacterial cell wall and a tail spike protein that subsequently binds irreversibly to other receptors on the cell wall. File phageP2.jpg thumb Enterobacteria phage P2 Phage P2 is a representative member of the Myoviridae There are three families in the order Caudovirales . The Siphoviridae have long flexible tails and constitute the majority of the tailed viruses. Myoviridae have long rigid tails and are fully characterized by the tail sheath that contracts upon phage attachment to bacterial host. The smallest family of tailed viruses are podoviruses phage with short, leg like tails . virus stub Category Bacteriophages ... more details
Multiple issues orphan March 2012 lead rewrite July 2011 notability July 2011 A precore mutant is a variety of hepatitis B virus. The HBV has four genes S, P, C, and X. The S gene codes for the major envelope protein HBsAg . The largest gene is P. It codes for DNA polymerase . The C gene codes for HBeAg and HBcAg. The C gene has a precore and a core region. If translation is initiated at the precore region, the protein product is HBeAg. If translation begins with the core region, HBcAg is the protein product. HBeAg is a marker of HBV replication and infectivity. The precore region is not necessary for viral replication. Precore mutants can replicate. They are readily detectable by HBV DNA in serum, but hepatitis B e antigen HbeAg is absent. The X gene codes for HBxAg. The product of the X gene is hepatitis B x antigen HBxAg . It may be involved in carcinogenesis . References http www.ncbi.nlm.nih.gov pubmed 1732124 http www.emedmag.com html pre gic consults 031504.asp Category Hepatitis ... more details
Vif may refer to Vif proper name VIF Internet , an Internet service provider in Montreal Vif, Is re Vif , a commune in France commune of the Is re d partement in France d partement in France Vif word Vif , a French tempo marking meaning lively or fast VIF abbreviation Valency interaction formula , a method for drawing molecular structural formulas Variance inflation factor , a measure of collinearity in statistical regression models Very Important Friend , an affectionate term Visiting International Faculty Program , a company, based in North Carolina , USA , that sponsors international teachers to teach in the USA. Value of in force , a life insurance term Virtual Interface , a networking term Viral infectivity factor of retrovirus es, specifically used in the context of HIV Vector Unit InterFace on PlayStation 2 Verify in field , a construction documentation term Vignerons ind pendants de France , an organisation that assists independent winemaker s in France . V lerenga Fotball , a Norwegian football club V lerenga Ishockey , a Norwegian ice hockey club V lerengens IF V lerengens Idrettsforening , a Norwegian sports club disambig da VIF es Vif fr VIF it VIF scn VIF sv VIF ... more details
italic title Plasmodium atheruri is a species of the genus Plasmodium subgenus Vinckeia . Like all members of this genus it is parasitic on vertebrate and insect host biology host s. The natural vertebrate host is the Africa n porcupine Atherurus africanus but it is possible to infect the large vesper mouse Calomys callosus and Meriones unguiculatus . Taxobox name Plasmodium atheruri image caption image image width regnum Protista phylum Apicomplexa classis Aconoidasida ordo Haemosporida familia Plasmodiidae genus Plasmodium species P. atheruri binomial Plasmodium atheruri Description This species was described in 1958 by den Berghe, Peel, Chardome and Lambrecht. Exoerythrocytic schizogony in this species usually lasts 4 to 6 days but occasionally schizont s have been found in the liver at day 8. Two types of infection are recognised an acute form characterised by large trophozoite s, schizonts with 8 to 16 merozoite s, gametocyte s and infectivity to Anopheles species and a chronic form following the acute form by 15 to 21 days and which is characterized by small trophozoites and schizonts producing 4 merozoites. Vectors Anopheles machardyi Anopheles smithii Anopheles stephensi Geographic occurrence This species is found in Africa . References Reflist DEFAULTSORT Plasmodium Atheruri Category Plasmodium plasmodium stub id Plasmodium atheruri ... more details
HPTN 052 is the name of a clinical trial which examined the extent to which antiretroviral therapy ART can, when taken by people who have HIV , decrease their infectivity and thereby reduce the chance that they will pass HIV on to their sexual partners. The results of the study were so compelling, that the study s Data and Safety Monitoring Board DSMB asked the research team to share the results with all study participants and offer ART to the control group before the study ended ref cite web last Matassa first Matt title Initiation of Antiretroviral Treatment Protects Uninfected Sexual Partners from HIV Infection HPTN 052 url http www.hptn.org web 20documents PressReleases HPTN052PressReleaseFINAL5 12 118am.pdf accessdate January 3, 2012 date May 12, 2011 ref . The study continues to determine if the results that ART can reduce the transmission of HIV by 96 have durability. The trial was organized by the HIV Prevention Trials Network HPTN . In December 2011, Science journal Science named the study as Breakthrough of the Year ref cite web url http www.niaid.nih.gov news newsreleases 2011 Pages HPTN052Breakthrough.aspx title HIV Study Named 2011 Breakthrough of the Year by Science first last work niaid.nih.gov year 2011 last update accessdate 24 December 2011 ref References reflist External links http www.hptn.org research studies hptn052.asp HPTN s page for HPTN 052 Category Clinical trials related to HIV ... more details
Taxobox Color parameter is not needed automatically assigned name Spumavirus virus group vi familia Retroviridae subfamilia Spumaretrovirinae genus Spumavirus type species Simian foamy virus subdivision ranks Species subdivision African green monkey simian foamy virus br Macaque simian foamy virus br Bovine foamy virus br Equine foamy virus br Feline foamy virus A spumavirus spuma , Latin for foam or foamyvirus is a genus of the retroviridae family biology family . Spumaviruses are exogenous viruses that have specific morphology biology morphology with prominent surface peplomer spikes . The virions contain significant amounts of double stranded full length DNA , and assembly is rather unusual in these viruses. Supumaviruses are unlike most enveloped viruses in that the viral envelope envelope membrane is acquired by budding through the endoplasmic reticulum instead of the cytoplasmic membrane . Some spumaviruses, including the equine foamy virus EFV , bud from the cytoplasmic membrane. Some examples of this virus are the chimpanzee foamy virus, simian foamy virus and the human foamy virus . While spumaviruses will form characteristic large vacuoles in their host cells while in vitro , there is no disease association in vivo . ref name Acheson cite book author Acheson, NH title Fundamentals of Molecular Virology edition 1st ed. publisher John Wiley & Sons year 2007 isbn 0 471 35151 2 ref References reflist Further reading Santillana Hayat M, Valla J et al. Inhibition of the in vitro infectivity and cytopathic effect of human foamy virus by dideoxynucleosides . AIDS Res Hum Retroviruses. 1996 Oct 10 12 15 1485 90. External links http www.ncbi.nlm.nih.gov books bv.fcgi?rid rv.section.7999 NCBI Spumavirus MeshName Spumavirus http www.expasy.org viralzone all by species 10.html Viralzone Spumavirus Retroviruses Category Spumaviruses virus stub de Spumaviren es Spumavirus ... more details
No footnotes date February 2011 Hemagglutination , or haemagglutination , is a specific form of Agglutination biology agglutination that involves red blood cell s RBCs . It has two common uses in the laboratory blood typing and the Virus Quantification quantification of virus dilutions. Blood Typing Blood type can be determined by using antibody antibodies that bind to the ABO blood group system A or B blood group in a sample of blood. For example, if antibodies that bind the A blood group are added and agglutination occurs, the blood is either type A or type AB. To determine between type A or type AB, antibodies that bind the B group are added and if agglutination does not occur, the blood is type A. In blood grouping the patient s serum is tested against RBCs of known blood groups and also the patient s RBCs are tested against known serum types. In this way the patient s blood group is confirmed from both RBCs and serum. A direct Coombs test is also done on the patient s blood sample in case there are any confounding antibodies. Viral Hemagglutination Assay Main Hemagglutination assay Many viruses attach to molecules present on the surface of RBCs. A consequence of this is that at certain concentrations, a viral suspension may bind together agglutinate the RBCs, thus preventing them from settling out of suspension. Since agglutination is rarely linked to infectivity, Fact date February 2009 attenuated viruses can therefore be used in assay s. By serially diluting a virus suspension into an assay tray a series of wells of uniform volume and adding a standard amount of blood cells, an estimation of the number of virus particles can be made. While less accurate than a plaque assay , it is cheaper and quicker taking just 30 minutes . This assay may be modified to include the addition of an antiserum. By using a standard amount of virus, a standard amount of blood cells, and serially diluting the antiserum , one can identify the concentration of the antiserum the great ... more details
Taxobox virus group iv familia Tombusviridae genus Dianthovirus The viruses of the genus Dianthovirus belong to the family Tombusviridae . Dianthoviruses are plant viruses . Examples of species of this genus include the type species, Carnation ringspot virus , Red clover necrotic mosaic virus and Sweet clover necrotic mosaic virus . The virus probably has a worldwide distribution 1 . The viruses can be and have been transmitted via nematodes , by mechanical inoculation, by grafting of plants and by contact between infected hosts with previously uninfected Host biology host 1 . Particles Viruses of this genus have round, non enveloped capsids with icosahedral symmetry and a hexagonal appearance 1 . The capsid is 31 35 nm in diameter. The buoyant density in CsCl of virions is between 1.363 1.366 g cm 3 1 . They have a sedimentation coefficient of 126 132 135 S20w 1 . The pH of their isoelectric point is 4.5 1 . The virions become inactive from about 80 90 C and are inactive above those temperatures. They are viable in vitro for about 50 70 days 1 . Treatment with ether either decreases or does not alter their infectivity 1 . No lipids have so far been reported 1 . Genome These viruses have segmented, bipartite genomes that are linear, positive sense, single stranded RNA 1 . These genomes are about 5300 nucleotides in length 1 . They have a methylated cap at the 5 end whose sequence type is m7GpppA 1 . The genome also codes for non structural proteins as well as structural proteins 1 . Three non structural proteins have been found 1 . References ICTVdB The Universal Virus Database, version 4. http www.ncbi.nlm.nih.gov ICTVdb ICTVdB External links http www.expasy.org viralzone all by species 633.html Viralzone Dianthovirus Category RNA viruses ... more details
Infobox rfam Name Picornavirus internal ribosome entry site IRES image RF00229.jpg width caption Predicted secondary structure and sequence conservation of IRES Picorna Symbol IRES Picorna AltSymbols Rfam RF00229 miRBase miRBase family RNA type Cis regulatory element Cis reg Internal ribosome entry site IRES Tax domain Virus es GO GO 0043022 SO SO 0000243 CAS number EntrezGene HGNCid OMIM PDB RefSeq Chromosome Arm Band LocusSupplementaryData This family represents the Picornavirus internal ribosome entry site IRES . IRES elements allow cap and end independent translation biology translation of mRNA in the host cell. It has been found that La autoantigen La is required for Coxsackievirus B3 CVB3 IRES mediated translation, and it has been suggested that La may be required for the efficient translation of the viral RNA in the pancreas . ref cite journal last Ray first PS coauthors Das S year 2002 title La autoantigen is required for the internal ribosome entry site mediated translation of Coxsackievirus B3 RNA journal Nucleic Acids Res volume 30 pages 4500&ndash 4508 pmid 12384597 doi 10.1093 nar gkf583 issue 20 pmc 137146 ref ref cite journal last Liu first Z coauthors Carthy CM, Cheung P, Bohunek L, Wilson JE, McManus BM, Yang D year 1999 title Structural and functional analysis of the 5 untranslated region of coxsackievirus B3 RNA In vivo translational and infectivity studies of full length mutants journal Virology volume 265 pages 206&ndash 217 pmid 10600593 doi 10.1006 viro.1999.0048 issue 2 ref References reflist 1 External links Rfam id RF00229 name Picornavirus internal ribosome entry site IRES molecular cell biology stub Category Cis regulatory RNA elements Category Internal ribosome entry site ... more details
does not alter the infectivity of the prions. Even when placentas have little PrPS sup C sup , kids ... is not directly proportionality proportional to infectivity. Factors affecting prion infectivity ... to analyze whether the detectable PrP sup Sc sup in the soil extracts still exhibited oral infectivity ... feeding. This indicated substantial amounts of persistent infectivity in soil that had been incubated ... infectivity of Mte and soil bound prions. The effects of prion source via infected brain homogenate ... of the prions is uncertain, but is not directly proportional to infectivity. Sheep ingest soil ... and infectivity of prions in the environment. Effective methods to inactivate prions in the soil are currently lacking, and the effects of natural degradation mechanisms on prion infectivity ..., assess their effects on prion infectivity, and determine which organism or organisms present in lichens ... more details
The hemagglutination assay or haemagglutination assay HA is a method of quantification for virus es or bacteria by hemagglutination . It is an easy, simple and rapid method which can be applied to large numbers of samples. Some viral families and many bacteria have envelope or surface protein s which are able to agglutinate stick to human or animal red blood cell s RBC and bind to N acetylneuraminic acid . As each of the agglutinating molecule attaches to multiple RBCs, a Bravais lattice lattice structure will form. The hemagglutination assay of a virus, in contrast to other forms of virus quantification such as a plaque assay or 50 Tissue Culture Infective Dose , does not give any measure of viral infectivity, because no virus replication is required in this assay. The same may not be true when using HA for bacteria. The detailed conditions depend on the type of virus or bacteria being assayed since certain pH values and ionic strengths can impact the activity of the proteins of interest in a difficult to predict manner. Normally, a virus dilution e.g. 2 fold from 1 4 to 1 4096 will be applied to an RBC dilution e.g. 0.1 to 0.7 in steps of 0.2 for approx. 30 min, often at 4C, otherwise viruses with neuraminidase activity will detach the virus from the RBCs. Then the lattice forming parts will be counted and the titer calculated. Virus concentration in virion s per Litre milliliter 10 sup 7 sup x HA titer . ref cite journal author Donald HB, Isaacs A title Counts of influenza virus particles journal J. Gen. Microbiol. volume 10 issue 3 pages 457 64 year 1954 pmid 13174769 doi ref The titer of a hemagglutination assay is determined by the last viable lattice structure found. This is because it is at the point where, if diluted anymore, the amount of Virus particles will be less than that of the RBCs and thus not be able to agglutinate them together. For bacteria, depending on species, a bacterial dilution will be applied to an equal part RBC dilution and then incubat ... more details
Unreferenced date December 2009 In virology , the multiplicity of infection or MOI is the ratio of infection infectious agents e.g. phage or virus to infection targets e.g. Cell biology cell . For example, when referring to a group of cells inoculated with infectious virus particles, the multiplicity of infection or MOI is the ratio of the number of infectious virus particles to the number of target cells present in a defined space. Interpretation The actual number of phages or viruses that will enter any given cell is a statistics statistical process some cells may absorb more than one virus particle while others may not absorb any. The probability that a cell will absorb math n math virus particles when inoculated with an MOI of math m math can be calculated for a given population using a Poisson distribution . math P n frac m n cdot e m n math where math m math is the multiplicity of infection or MOI, math n math is the number of infectious agents that enter the infection target, and math P n math is the probability that an infection target a cell will get infected by math n math infectious agents. In fact the infectivity of the virus in question will alter this relationship. One way around this is to use a functional definition of infectious particles rather than a strict count, such as a plaque forming unit . For example, when an MOI of 1 1 viral particle per cell is used to infect a population of cells, the probability that a cell will not get infected is math P 0 36.79 math , and the probability that it be infected by a single particle is math P 1 36.79 math , by two particles is math P 2 18.39 math , by three particles is math P 3 6.13 math , and so on. The average percentage of cells that will become infected as a result of inoculation with a given MOI can be obtained by realizing that it is simply math P n 0 1 P 0 math . Hence, the average fraction of cells that will become infected following an inoculation with an MOI of math m math is given by math P n 0 ... more details
Infobox short story See Wikipedia WikiProject Novels or Wikipedia WikiProject Books name Breeds There a Man...? title orig translator author Isaac Asimov country United States language English language English series genre Science fiction short story published in Astounding Science Fiction publication type Periodical publisher Street & Smith media type Print Magazine , Hardcover Hardback & Paperback pub date June 1951 english pub date preceded by followed by Breeds There a Man...? is a science fiction short story by Isaac Asimov . It was first published in the June 1951 issue of Astounding and reprinted in the 1967 collection Through a Glass, Clearly and the 1969 collection Nightfall and Other Stories . Plot summary Elwood Ralson, a brilliant but psychologically disturbed physicist , becomes convinced that humanity is a kind of genetics experiment being run by an extraterrestrial life alien intelligence. His behaviour becomes more erratic and suicidal as his thoughts become more entrenched in this idea, and his health fails. He draws an analogy between human progress and the growth of bacteria that suggests that humanity has been bred in certain strains for various traits i.e artistic ability and that such breeding is what produced the Athens of Pericles and the Renaissance . He further states that the experimenters use a penicillin ring, or killing boundary, that makes humans want to kill each other should their abilities grow too great, as mental increase leads to greater infectivity, and humanity is dangerous to the experimenters. The most recent strain began with the Industrial Revolution , and its development for over a century has made it extremely dangerous. Therefore, the theoretical experimenters intend to use the atomic bomb to incite industrialized nations to kill each other. He claims that the aliens are exerting pressure on his mind to kill himself before he can help produce a defence against atomic weapons , since such a defence would protect humanity ... more details
italic title Taxobox color lightgrey name Mycobacterium africanum regnum Bacterium Bacteria phylum Actinobacteria ordo Actinomycetales subordo Corynebacterineae familia Mycobacterium Mycobacteriaceae genus Mycobacterium species M. africanum binomial Mycobacterium africanum binomial authority Castets et al. 1969, ref Castets, M., N. Rist, H. Boisvert. 1969. La vari t africaine du bacille tuberculeux humain. M decine d Afrique Noire, 1969, 16, 321 322. ref ATCC 25420 Mycobacterium africanum is a species of Mycobacterium that is most commonly found in West African countries. The symptoms of infection resemble those of M. tuberculosis . It is a member of the Mycobacterium tuberculosis complex . ref name pmid20350321 cite journal author Vasconcellos SE, Huard RC, Niemann S, et al. title Distinct genotypic profiles of the two major clades of Mycobacterium africanum journal BMC Infect. Dis. volume 10 issue pages 80 year 2010 pmid 20350321 pmc 2859774 doi 10.1186 1471 2334 10 80 url http www.biomedcentral.com 1471 2334 10 80 ref Epidemiology M. africanum is most commonly found in West African countries, causing up to a quarter of cases of tuberculosis in countries such as the Gambia. It is an infection of humans only and is spread by an airborne route from individuals with open cases of disease. It has a similar degree of infectivity to the regular M. tuberculosis organism but is less likely to progress to clinical disease in an immunocompetent individual. M. africanum is more likely to progress from infection to causing disease in an HIV positive patient, hence in countries where M. africanum is endemic, it represents an important opportunistic infection of the later stages of HIV disease. Pathogenesis It is not fully understood how the genetic differences between M. africanum and M. tuberculosis give rise to the lower pathogenicity of the former. However, it is known that the Region of Difference 9 RD9 is lacking in M. africanum but present in M. tuberculosis Brosch, et ... more details
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