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16 Pages

Natural Science
Course Code
NATS 1670
Mordechay Anafi

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rdJanuary 23 2012 Diversity of VirusesViruses are highly diverse in overall morphologyin the nature of their genetic materialDifferent method of replicationDifferent structure and sizehost range Host Range Host range may be wide or narrowOnly one species eg humanAnimalinsect humanAnimal human rabiesdo not cross eukaryoteprokaryote boundary Factors Affecting Host Range Cell surface receptor ex polio can only affect human beings most important part of specific relationship viruses to host whowhat is receptive to virusAvailability of replication machineryherpescan replicate because is coming with own enzyme has the ability to cross certain boundaries use cell to replicate virus ability of virus to replicateability to get out of the cell and spread to move out of one cell and affect others as wellex trying to fight influenza by inhibiting the specific enzyme that allows it to spreadtrying to get virus to not be able to leave cell to make more virusmaking protein 15 of genome 8 of genome is made of sequences of old viruses that werent able to get outHost antiviral responseevery virus that can affect us has some ability to overcome our immune system to escape our antibodies etc HIV ex of this all those factors affecting host range affect the type of cell infected and the tissue infected diseaseWhen u feel sick after being infected with a virus flue it means your interference system is workingZoonotic VirusesZoonotic viruses pursue their biological cycles chiefly in animalsInsectsHumans are secondary or accidental hostsif affect human just happen to be at the wrong environment which normally we are not inThese viruses are limited to areas and environments able to support their nonhuman natural cycles of infectionLimited to certain parts of the environmentvertebrates or arthropods or bothVideoas ppl go into new environments that previously were not available to humans the viruses in these new areas now look for new hosts and find themso new viruses dont come out of nowhere as we create new areas they get outImplications of Zoonotic Viruseshost rangepreventionseverity of diseaseinfluenza considered severe disease because different types of cells and large amounts of cells get infected destroys cells new cells created and later on can get secondary infectiondiagnosis try find cause of infection find hostmethod of replicationtreatmentbased on the lifecycle of the virus In order to control viral diseaseneed knowledge of virusreservoirsex rabieswe know certain animals can carry virus with no symptoms living for 40 years or so passing it onso controlling this populationway to reduce transmissionmode of transmissionHIVsexually transmitted etcmethods to inactivate the virusvaccines antiviral drugsdevelopment of drug resistancepplvirus becomes resistant to drugs Effects of the Virus on the Host January 27 2012May inhibit host DNA RNA or protein synthesisMorphological changes the cells that are infected with viruses look and function differentlyCell death from lack of essential proteinsLysisNonenveloped viruses must escape from the host cell by killing the cell through lysis Enveloped cells can exit through means of forming vesicles around the virus so that it may exit without harming the cell membraneViruses also activate the immune system to attack against the infected cellsApoptosisa self destruct sequence that the cell may undergo after realizing it has been infectedExample Hepatitis virusProduce abnormal proteins the proteins that the virus is making is causing the diseaseEbola virus activates blood coagulation Be4cause we have a limited amount of proteins platelets in the blood this spontaneous coagulation will result in a lack of coagulating factors which often leads to death due to internal bleeding we often have broken blood vessels within the body that go unnoticed because of the efficiency of our coagulating factorsEbola virus kills 90 of those infected although it doesnt normally appear as an outbreak outside of its natural African LocalitiesIndefinite growth cancerConsequences of viral infectionsAsymptomatic most cases there is no effect or the effect is very mildSuffering followed by recoveryPersistent chronic diseaseCongenital diseaseNeonatal Rubella German Measlesalthough appears as only a mild rash in adults it can have serious side effects on an unborn fetus especially in the first trimester altering the development of neurons 75 of infected babies are born normal but will experience mental retardation throughout their life 25 of schizophrenia patients are born babies infected with Rubella but more research is needed to confirm a link between the twoContributory factor in cancerContributory factor in other diseasesDiabetes Multiple SclerosisSome viruses are similar to our own proteins so as we build immunity to the foreign antigens our immune system started to attack the similar looking proteins of our ownFatal disease
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