Introduction break the balance and cause problems,

Introduction·       Viral Nanotechnology provide general idea about fast developing in the field ofimmunology, virology, microbiology, chemistry, physics, and mathematicalscience. Its role is  by leadingresearchers and practitioners, making it both inclusive  and essential  resources for study and research.

·       by increasing demand of the applications the viralnanotechnology is quickly expanding ·       Viral nanotechnology characterized Similarly as An note worthyscience  that concerns itself with how toutilize  the sub-atomic modules thoseunique separate science of molecular engineering only constructs. chances torevolutionize practices in energy, biomedicine, health care, photonics,catalysis, electronics, and public health are diverse by present potentialapplications of viral technology ·       the demand  for newmethods and techniques  in theprevention, diagnosis, and treatment of disease is considered as reasons forfast growth of Viral Nanotechnology. There is also great application to be usedas methods for diagnostics, including the development of diagnostic substancesand novel imaging technologies for detecting disease and infectious agents (1)·       What is Virus?Viruses are small infectious agent that can exist everywhere ,their diameters in nanometers level. it’s found in air, soil  animals and human bodies.  but most of them are harmless. Human immunesystem protect the body against virus by generating antibodieswhich  will recognize the virus and destroy it.The  viruses can break thebalance and cause problems, diseases when the human immune system is weak dueto multiple reasons, so called opportunist pathogen.Viruses depend on the hostfor their survival and reproducing.

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Viruses have many important functions forhumans, plants, animals, and the environment. such as  some of them protect the host against otherinfections , by transferring genes among different species. In biomedicalresearch, scientists use viruses to insert new genes into cellsStructure of a virusVirus particle composed of threemain parts:·       Nucleic acid  ( DNA or RNA ) core of the virus  DNA or RNA holds all of the information forthevirus and that makes it unique andhelp to multiply.·       Protein Coat (capsid) –coveringover the nucleic acid which  protect it.·       Lipid membrane (envelope) – which covers thecapsid. naked viruses haven’t envelop Life cycle of a basic viruslytic cycle include :1.

    Adsorption process in which virus particleattaches to a host cell. 2.    Entering DNA or RNA by inject the host cell.3.    replication process by cellular enzymes which start making new virus particles 4.

     Relaease of the virus by  newly formed viruses that kill the cell then andsearch for a new host cell.    II.           Different Types of Virus.

There are four main morphological virus types:Helical·       It composes of a single capsomere stacked around a central axisto form a helical structure·       rod-shaped or filamentous virions·       short and highly rigid·       long and very flexible.·       The genetic materials, (DNA or RNA ), single-stranded RNA, butssDNA in some types , connected to the protein helix by interactions betweenthe negatively charged nucleic acid and positive charges on the protein.·       Overall, the length of a helical capsid is related to the lengthof the nucleic acid contained within it·       examples as tobacco mosaic virus IcosahedralMost infections viruses are icosahedral or close spherical withchiral icosahedral symmetry. A normal icosahedron is the ideal method forforming a close shell from sub-units. each triangular face has 3 identical capsomeresthat give 60 forit. Numerous viruses as rotavirus, have more than 60 capsomers and sphericalshape.Capsomeresare  surrounded by hexonsthey might be made out of various proteins.

EnvelopeA few types of viruses covered themselves one of the celllayers, either the external film encompassing a contaminated host cell orinternal layers, for example, endoplasmic reticulum  or nuclear layer  get external lipid bilayer known as a viral envelope. This film is decorated by proteins coded for viral genome and host genome; The flu and HIV virusesutilize this techniqueComplexThese infections have a capsid that is neither helical noricosahedral, and that may have additional structures, as protein tails or acomplex external layer. for example, Enterobacteria phage T4, have bogglingcomposition comprising of an icosahedral head to a helical tail, which may have a hexagonal base plate with projectingprotein tail Virus has two types, DNA virus and RNA virus. The genome of DNAvirus is consisted of DNA, and similarly RNA is the genetic material of a RNAvirus.

 III.           Effect of Virus on human Health  Living organisms as animals,plants, fungi, and bacteria are all subject to be infected by viral infection. HoweverViruses select specific type of cells which want to invade. What does the role of host  in order to fight off  a virus invasion ? “immune response.

” whichis created by Immune system  produceantibodies to protect the host against any foreign substances. Antibodies arespecific to each type of intruder, and new set of antibodies will have to be formedfor each new disease of infection. This process take several days. In the meantime,”interferons.

“which is produced by the cell infected by virus immediately to protect adjacentcells production of antibodies.the benefit of interferon in viral treatment isstill under research and the  mechanismstill case if viral infection ,antiviral infection can be prescribed. List ofdiseases caused by viruses  IV.           Diagnostic Methods of viruses 3 categories:(1) Direct detection(2) Virus isolation(3) Serology.1. Direct Examination of SpecimenClinical specimen examined directly for the presence of virus particles,virus antigen , and viral nucleic acids.

·       Electron Microscopy morphology /immune electron microscopy·       Light microscopy histologicalappearance – e.g. inclusion bodies·       Antigen detectionimmunofluorescence, ELISA etc.·       Molecular techniques for thedirect detection of viral genomes 2. Indirect Examination = VirusisolationØ Cell Culture·       Cytopathic effect·       Haemadsorption·       Confirmation by neutralization,interference·       Immunofluorescence etc.

Ø Eggs pocks – haemagglutination, inclusion bodiesØ Animals disease or death confirmation by neutralization 3. SerologyTitres increase of antibody between acute and convalescentstages of  infection , detection of IgMin primary infection.Classical Techniques ·       COMPLEMENT FIXATION TESTS (CFT)·       HAEMAGGLUTINATION INHIBITIONTESTS·       IMMUNOFLUORESCENCE TECHNIQUES(IF)·       NEUTRALIZATION TESTS·       SINGLE RADIAL HAEMOLYSISNewer Techniques·       RADIOIMMUNOASSAY (RIA)·       ENZYME LINKED IMMUNOSORBENT ASSAY(ELISA)·       PARTICLE AGGLUTINATION·       WESTERN BLOT (WB)1.

Virus IsolationForvirus isolation cultured cells, eggs and laboratory animals are used. Cellcultures more widely used for virus isolation in many laboratories. For cellculturespreparation, tissue fragments are first dissociated, by using  trypsin or collagenase. The cell suspension isthen placed in a flat-bottomed glass or plastic container (petri dish, a flask,a bottle, test tube) together with a suitable liquid medium.

e.g. an animalserum. After a variable slack, the cells will attach and spread on the bottomof the container and then isolation is started. Primary and Secondary CulturesPrimarycultures are performed by replacing the fluid two or three times per week .thecells are separated from the vessel wall by either trypsin or EDTA since thecultures become too crowded, and the remaining portions are used to initiatesecondary cultures.Inboth primary and secondary cultures, the cells keep some of theircharacteristics from which tissue they are derived.Cellcultures are separated into 3 types:-1.

     Primarycells -which are derived from animal or human tissues and can be sub-cultured only onceor twice e.g. primary monkey.

2.     Semi-continuousdiploid cells – which are prepared from human fetal tissue and can be sub-cultured20 to 50 times e.g. human diploid fibroblasts .3.     Continuouscells -originate  fromhuman cancer cells oranimal tissue e.

g. Cellcultures vary greatly in their susceptibility to different viruses. precautionsin cell culture :·       Transportation of Specimens to thelaboratory should be as soon as possible once it’s taken.·        Swabs should be placed in a bottle containingvirus transport medium.·         Bodily fluids and tissues should be kept in asterile container.¢ Identificationof a specific virus grown in infected cell cultures can be performed byneutralization of infectivity, hemadsorption inhibition, and mmunofluorescence.

 Effects of productive viralreplication in cell culture:·        Cytopathiceffect(s) (CPE) as in mumps and measlesviruses·        Syncitia(cell fusion)·        HemadsorptionAdvantages of cell culture for virus diagnosis :·        Relativeease·        broadspectrum ·        Sensitivity.Limitations:·        Longperiod (up to 4 weeks) required for result.·        Susceptibleto bacterial contamination.·        Susceptibleto toxic substances which may be present in the specimen.

·        Manyviruses will not grow in cell culture e.g. Hepatitis B, Diarrheal viruses,parvovirus, papillomavirus. ·        Difficultyin obtaining cell cultures.             Left:Haemadsorption of redblood cells onto the surface of a cell sheet infected by mumps virus. Also notethe presence of syncytia which is indistinguishable from that of RSV (Courtesyof Linda Stannard, University of Cape Town). Right: Positive CMV DEAFFtest. (Virology Laboratory, Yale-New Haven Hospital)2.

Electron MicroscopyIt’s used for detection andidentification of virus’s morphology by EM.Advantages:·        Visualizationof virus·        Directidentification of virus ·        Rapiddiagnostic toolDisadvantages:·        Difficultto analyze multiple specimens·        Availableof minimum number of virus (around 106 virus particles per mlfor detection)·        Detectionis difficult for some viruses as SRSV·        Expensive·        Highlyskilled personnel are required.Types of EM methods;-1.     DirectEM:negativestaining is used, small special equipment is required , Samples should be concentrated prior negativestaining by different methods as differential centrifugation,ammonium sulphateprecipitation2.     Immunoelectronmicroscopy (IEM). High sensitivity and specificity It’s used in the following situations:·        Smallnumber of virus particle are available.·        Viruswhich have different morphological shapes as herpes viruses and picornaviruses·        Inan outbreak conditions 3.

Haemagglutination Inhibition Testviruses directly agglutinate erythrocytes by bindingto specific receptor sites on the surfaceof the erythrocyte and this characteristic can be used in detection,identificationandquantitationof thevirusSome virus will have ability to bindto erythrocytes (red blood cells), causing the formation of a lattice. This characteristicis called hemagglutination, Antibodies against the viral protein prevent virus to agglutinatethe erythrocytes , it’s known haemagglutination-inhibition test (HAI)It’s widely used for the diagnosisof rubella and influenza virus infections.Advantages:·       Rapidin detection and identification of virus(few hours)·       Cheap ·       Easily preparedDisadvantages:·       Non- specific·       low sensitivity 4. ELISA (enzyme-linkedimmunosorbentassay ) enzyme-linkedimmunosorbent assay (ELISA) was developed in 1970 ,also known as solid-phase enzyme immunoassay. It is biochemicaltechnique mainly used to detect the presence of specific antibody or antigen inthe sample. It has been used as marker for disease diagnosis.

Varioustechniques can be used in ELISA, the most important one are:1.     Competitive assay2.     Sandwichassay3.     IndirectassayAdvantages:VerysensitiveQuantitative§  Competitivemethod§  It’sAg-Ab complex.§  competitivereaction between antigen bound with primary antibody in plate and antigen existin the sample.§  highlysensitive.§  Intensity of color is inversely proportional tothe concentration of antigen present in the sample.(a) Sandwichmethod§  Insolubilized antigen binds to theanalyte (the antibody) in the sample specifically,§  addition of labelled enzyme linkedsecond antibody that binds to primary antibody.

§  Unbound antibody-enzyme conjugates are washedoff.(b)Indirect assay§  It’sused for detection of antibody present in the sample.§  Primaryantibodyexist in the specimen bind specifically to the antigen§  toremove unbound antibodies wash the solution.§  enzymewill conjugate secondary antibodies.§  colorchange after addition enzyme substrate.§  Intensityof color direct proportional to concentration of primary antibodies.

§  Cross-reactivitymight occur§  Anextra incubation step is requiredAssayCharacteristics :1.    Higher sensitivity; – either by selection of antibodies with a extremely highaffinity, or by reduction of the height and variability of the backgroundreaction, which makes very low concentrations of analyte more readilydetectable.2.    Higher specificity;- by avoiding the presence of any antibodyin the assay system with specific reactivity against non-analyte epitopes, andby selecting combinations of monoclonal antibodies which may further increasespecificity.

3.     Higher practicality; – e.g. by introducing simultaneous incubation of label,solid phase and sample without risk of “prozone effect”.5. Single Radial Haemolysis Single radial haemolysis (SRH) is usually used for the detection of rubella-specific IgG. Multiple serum can be analyzed simultaneously to confirm the immunity by SRH sensitive, specific, and reliable.   6.

Immunofluorescense Immunofluorescence (IF) is commonly used for rapid analysis of virusinfection.basic principle by using afluorescein- labelled antibody to stain specific virus antigens present in thesamples, so that the stained cells fluoresces under UV illumination.Direct IF, the specimen is probed directly with a specific labelledantibody against specific  virus antigen.Indirect IF, the specimen is first probed with a non-labelled specificantibody, followed by a labelled antibody against the first has  extra amplification step.§ Detectionof virus antigen can be done by direct IF or indirect IF§ Detectionof virus antibody can be determined always by indirect IF


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