Veterinary Virology Lecture Notes PDF

Veterinary Virology Lecture Notes - lipid solvents (e.g. sodium Prepared by Khristine Kaith S. Lloren, DVM, MSc, PhD deoxycholate) are used in College of Veterinary Medicine and Agricultural Sciences enveloped vir...

Veterinary Virology Lecture Notes - lipid solvents (e.g. sodium Prepared by Khristine Kaith S. Lloren, DVM, MSc, PhD deoxycholate) are used in College of Veterinary Medicine and Agricultural Sciences enveloped viruses to solubilize the virion and release the components I. Vaccines against Viral Diseases - e.g. glycoprotein spikes of the Types of Vaccines viral envelope A. Live-attenuated virus vaccines C. Vaccines produced using - elicits a lasting immune response while recombinant DNA and Related causing little or no disease Technologies (novel technologies) - mimics a subclinical infection a. Attenuation of Viruses by Gene a. Avirulent Viruses in Heterologous Deletion or Site-Directed Species Mutagenesis b. Attenuation of viruses by serial - Deliberate insertion of passage in cultured cell several attenuating c. Attenuation of viruses by serial mutations into key viral passage in heterologous hosts genes or completely d. Attenuation of viruses by selection deleting nonessential genes of mutants and reassortants that contribute to virulence B. Nonreplicating Virus Vaccines b. Subunit vaccines produced by expression of viral proteins a. Inactivated (Killed) Whole - Utilizes eukaryotic Virions expression vectors such as - usually made from virulent plant and yeast cells, insect viruses that are killed through cells and various chemical or physical agents but mammalian cells still maintain immunogenicity - The gene of a viral protein - remarkably safe but requires may be cloned into the large amounts of antigen to elicit expression plasmids and antibody response expressed in any of several - usually formulated with chemical cell systems adjuvants to enhance immune response c. Viral Proteins that Self- - examples of inactivating agents: Assemble into virus-like formaldehyde, β-propiolactone, particles (VLPs) and ethylenimine - Some nonenveloped icosahedral viruses have b. Purified Native Viral Proteins capsid proteins that self-  assemble into virus-like define whether an animal has ever particles (VLPs), which can been infected by a particular virus be used as vaccines determine if a specific virus (or - Recombinant VLPs are other pathogen) is linked to a devoid of viral nucleic acid clinical event and therefore completely determine if an animal has safe responded to a vaccination - serum → sample of choice for d. Viruses as vectors for serological assays Expression of Heterologous Viral Antigens A. Enzyme Immunoassay – Enzyme- - Recombinant DNA linked Immunosorbent Assay (ELISA) techniques enable the - serologic assays of choice for the insertion of foreign genes qualitative (positive or negative) or into viral genomes, allowing quantitative determination of viral gene expression in target antibodies cells - rapid, relatively cost-effective - may not require the production of e. DNA vaccines infectious virus for antigen if recombinant - A type of vaccine that uses a antigens are used bacterial plasmid to - Procedure: introduce DNA sequence Viral antigen is bound to a solid matrix (encoding an antigen) into → Serum is added → if antibodies to the an individual’s cells antigen are present in the sample, they - a recombinant eukaryotic bind to it → the bound antibody is expression vector that detected by an anti-species antibody encodes a certain protein tagged with an enzyme → With addition antigen and is directly of the enzyme substrate, a color reaction injected into animals develops that can be assessed either visually or with a spectrophotometer II. Detection and Quantitation of virus- specific antibodies B. Serum (Virus) Neutralization Assay (Serological Diagnosis) - has historically been the gold standard - measures only one limb of the adaptive for the detection and quantitation of immune response which is the humoral virus-specific antibodies immunity - considered a direct correlate of - measurement of antibody responses protective antibody in vivo remains a valuable technique for defining - the basis of the neutralization assay is the infection status of animals the binding of antibody to infectious virus, - Uses of serological tests: thus preventing the virus from initiating an infection in a susceptible cell E. Immunodiffusion - agar gel immunodiffusion (AGID) C. Immunoblotting (Western blotting) assays were used for specific diagnosis - simultaneously but independently of a number of viral infection and measure antibodies against several disease (e.g. hog cholera, influenza, proteins of the agent of interest equine infectious anemia) - key steps include: - Coggins test → an AGID that detects 1. Protein separation using SDS Page antibodies to the Equine Infectious 2. Separated proteins are transferred Anemia in a horse’s blood onto a nitrocellulose or PVDF - strictly qualitative =provides a simple membrane yes/no answer 3. The membrane is treated with a blocking agent Reference: 4. Primary Antibody Incubation Maclachlan, N. J., & Dubovi, E. J. (Eds.). 5. Secondary Antibody Incubation (2016). Fenner's veterinary virology. 5th 6. Signal is visualized using ed. Academic press. chemiluminescence, fluorescence, or colorimetric detection D. Hemagglutination-Inhibition Assay - widely used for viruses (e.g. influenza, parainfluenza) that hemagglutinate red blood cells of one or another species - Priniciple: Virus binds to red blood cells through receptors on their surface → antiviral antibodies bind to these receptors and block hemagglutination - The reciprocal of the highest dilution of serum that inhibits the agglutination of the red blood cells by the standardized amount of virus represents the hemagglutination- inhibition titer of the serum