Veterinary Virology A Flashcards
Father of microscopic / virologic/ infectious diseases sciences
Louis Pasteur
Discovered the nature of prions, the etiologic agent of bovine spongiform encephalopathy, scrapie, and similar diseases. He was awarded a nobel prize in medicine.
Prusiner (1997)
Worked on inactivation of virus and attenuation of polio vaccine
Salk nd Sabin (1954-1057)
Identified Human Immune deficiency virus
Luc Montagnier et al (1984)
Made the first rabies vaccine
Louis Pasteur
First cancer causing virus to be discovered
Avian leukemia virus
Completely dependent on their host for the machinery of energy production and synthesis of macromolecules
Viruses
Made visualization of viruses possible
Electron microscopy
The first virus to be discovered where it was described as filterable viruses
Foot-and-mouth virus
The largest of the viruses of vertebrates
Pox virus
The morphologically defined protein coat surrounding the complete virus particle
Capsid
Morphologic units that are discemable features (protrusion or depression) seen on the surface of virions by electron microscopy
Capsomeres
Glycoprotein dimmers/trimmers assembled on virus surfaces as spikes
Peplomers
Symmetry found in isometric viruses
Icosahedral
Enzymes in NA replication, transcription, translation and shut down of host cell functions
Non structural proteins
Used in classic studies of virus replication in cell culture where in the increase of infectious virus over time is followed by sequential sampling and filtration
One-step growth curve
After infection of cell culture, a period that occurs wherein infectious particles cannot be demonstrated even intracellularly
Eclipse period
What process initiates viral infection
Attachment
What mechanism do viral uptake or penetration occur
Receptor mediated endocytosis and fusion with plasma membrane
Strategies of replication of RNA viruses are diverse because (3)
-Some are single or double stranded
-Some are positive or negative sense
-Some are monopartite or segmented
Gene sequences upstream from the start site which regulate transcription
Enchancer
Important for regulation of gene and involved in the amplification of transcription
Promoters
A type of viral protien, which act on non-infected cells to modulate the progress of infection in the body as whole
Virokines
What viral property is onvolved when viruses produce proteins that interfere with specific host antiviral activations
The capacity to elude host defenses
General types of genotypic mutation (3)
Point mutation
Chromosome mutation
Copy number variations
Types of point mutation (3) SID
Substitution
Insertion
Deletion
Types of chromosomal mutation (4)
Inversion
Deletion
Duplication
Translocation
Types of Copy number variation (2)
Gene amplification
Expanding trinucleotide repeat
Enhances spontaneous mutations for RNS virus
Defective interfering mutants
Vertebrate viruses with specific tropism and infection making them valuable in carrying foreign genes
Viral vectors
Viral mutants that cannot grow under certain experimental parameters (restrictive) but can replicate in others (permissive)
Conditional lethal mutants
T particles of vesicular stomatitis virus are type of mutants. They are shortened and cannot replicate by themselves but need the presence of parental wild-type virus
Defective interfering mutants
Observed in infection of cells by 2 viruses where progeny virions have acquired phenotypic characteristics from both parents although their genetype remains unchanged
Phenotypic mixing
Used to describe interactions betweeen viral proteins in doubly infected cells that result in rescue or increased yields of one or both viruses
Complementation
The heritable condition of possesing more than two complete sets of chromosomes
Polyploidy
Comprise a class of virus-coded proteins that are not required for viral replication but influence pathogenesis of infection in vitro by sabotaging the host’s innate resistence of immune response
Virokins
An immune response gene which aids in the host’s resistance to viral infections
Ir gene
Recombinant DNA technology involve molecular cloning which can be described as
-Insertion of foreign DNA segment into an appropriate vector in frame with appropriate upstream and downstream regulatory sequences
-The recombinant plasmid is introduced into the host cell
-The foreign DNA may be expressed and the protein it specifies may be produced in large amounts
A virus is associated with genetic shift and drift, especially regarding envelope proteins, hemagglutinin (H) and neuramidase
Influenza A
A viral strategy causes autoimmune damage because of presence of structural homoligies linear or confrontational between host and viral proteins
Molecular mimicry
Type of infection that is characterized by the non-demonstration of the virus except when reactivation of the disease occcurs
Persistent infection
Type of infection characterized by non-demonstration of the virus except when reactivation of the disease occurs
Latent infection
A viral strategy to evade the host defenses by establishing chronic infections in their host without killing the cell in which they replicate
Evasion by noncytocidal infection
An example of viral infection\s that causes damage to the immune system, thus exacerbating the severity of disease or predisposing the host to super infection with other infectious agents (2)
Infectious Bursal Disease (Chickens)
AIDS (Humans)
Type of viral infection where in the infectious virus gradually increases during a very long preclinical phase
Slow infection
Aids respiratory viruses to spread along the airway
Cilial beating
Two effective cleaning systems of the respiratory tract
Cilial beating
Mucus from Goblet cells
Virus causing damage to the epithelium of the intestinal tract by destroying diving crypt epithelium and removing short lived villus epithelial cells
Parvovirus
A part of intestinal tract that is rarely infected by viruses
Esophagus
Intestinal viruses protected during passage through the stomach of young animals by the buffering action of milk
Coronavirus
The capacity of virus to selectively infect cells in particular organs
Tropism
Viruses that are transmitted by and replicate in arthropod vectors
Arboviruses
Viruses that are transmitted via direct contact and replicate in stratified epithelia of host
Papillomaviruses
Viruses that are transmitted via aerosol droplets and replicate in the cytoplasm of the host cell
Paramyxoviruses
Viruses that are transmitted through rodent scratches, bites, and bodily fluids and replicate direct via viral infection of endothelial cells resulting in vascular dysfunction and shock
Arenaviruses
Capacity of virus to selectively infect cells in particular organs. This depends on viral and host factors. On the cellular level, there must be an interaction between viral attachment of proteins and matching cellular receptors. Receptors of certain viruses are usually restricted to certain cell types in certain organs; only these cells can be infected. Enhancers are required for productive infection. These are short, often tandem repeated sequences of nucleotides that can regulate specific transcription. Examples: papillomavirus DNA contains enhancers that are active in-keratinocytes and only infect and replicate in these cells
Tropism
Virus infection involves the Trojan Horse mechanism in its pathogenesis
Lentiviruses
Mechanism of invasion done by Lentiviruses, where the virus invades the cartilage inside monocytes/macrophages that line the sinusoids of the liver. They migrate across capillary or sinusoidal walls (diapedesis)
Trojan Horse Mechanism
The quantitative or relative measure of the pathogenicity of an infecting virus
Lethality
The dose of virus required to cause death in 50% of animals
Lethal dose 50
Virus titers can be expressed as follows (3)
Tissue culture infectious dose 50 (TCID5Q)
Lethal dose 50 (LD50)
Plaque forming units
Measurement of viral transmission in a population
Reproduction number
Describe live-virus vaccines
-Vaccines from naturally occurring attenuated viruses
-Vaccines using temperature sensitive (ts) mutants
-Vaccines using cold adapted mutants
Example of non-replicating native antigen vaccine
Vaccines produced from purified naturally occurring viral proteins
Examples of vaccines produced from inactivated whole virions
Rabies
FMD
Examples of vaccines produced from purified native viral proteins
Influenza viruses
Example of vaccine produced from purified naturally occurring viral proteins
Human hepatitis B virus
Category of vaccines which uses purified surface antigen of the virus (HbsAg)
None that is of veterinary importance
What does genetic surgery for viral vaccine development involve? (2)
Deletion of nonessential genes that contribute to virulence
Vaccines produced by attenuation of viruses by gene deletion of site- directed mutagenesis
Example of vaccine that uses genetic deletion, what gene it deletes
Pseudorabies vaccine: thymidine kinase (TK)
Viruses with the replicative machinery of one virus and protective antigen of another
Viral chimeras
Vaccines containing antibodies produced against the antigen binding site of an antibody against a virus
Anti-idiotypic antibody vaccines
Factors that affect vaccine efficacy and safety (3)
Genetic instability
Reverting toward virulence
Virus transmission within the population at risk
A recombinant vaccine that is dispensed using a “gene-gun”
DNA vaccines
Greatest risk in live virus vaccines
Contaminating virus
Questions to consider when designing vaccination programs
-The number of secondary cases arising from a single primary case
-The epidemiology of the virus
-The time to vaccinate
Factors should be considered when deciding the optimal age for vaccination: (3)
-Is the environment highly contaminated?
-Are there intense activities of arthropod vectors?
-Window of susceptibility
Measures the incidence of chronic diseases; the ratio at a particular point in time of the number of cases currently present in the population divided the number of animals in the population
Prevalence rate
Refers to the presence of multiple continuous chains of transmission resulting in the continuous occurrence of disease in a population over a period of time
Endemic diseases
Study of determinants, dynamics and distribution of diseases in a population
Epidemiology
Refers to peaks in disease incidence that exceeds the endemic baseline or expected incidence of disease.
Epidemic
Disease surveillance involves
-Systematic and regular collection of information
-Collection and analysis of data on disease occurrence
-Detect trends of changes in the distribution of disease
Methods of controlling disease
-Hygiene and sanitation
-Elimination of arthropod vectors
-Quarantine
A laboratory diagnostic test involving direct identification of viruses
Detection of electron microscopy
Diagnostic tests involving direct of viral nucleic acid
-Hybridization methods
-PCR
A method involving in vitro amplification of viral DNA
Polymerase chain reaction
The gold standard in viral diagnosis
Cell culture methods
After virus inoculation, what are cell cultures inspected for?
For the development of cytopathic effect
A technique where, during viral inoculation, when no cytopathic effect (CPE) is seen, supernatant fluid usually after freezing and thawing several times are inoculated into fresh monolayers after which CPE is observed.
Blind passage
A measure of its capacity to discriminate the presence of antibody directed against one virus versus another
Specificity of an immunoassay
Description of viruses under the family Popovaviridae (3)
-Replicates in the nucleus
-nonenveloped
-Spherical and icosahedral symmetry.
Description of papillomaviruses (3)
-Produce warts in many species
-Replication is in the nucleus
-The primary lesion is in the cell of the stratum germinativum
Where are rice grain papillomas found?
Teats
Description of Bovine papillomas or warts caused by Bovine papillomavirues 1, 2 and 5
-They have fibrous core covered to a variable depth with stratified squamous epithelium
-Hyperkeratinized outer layers
-Vary from small firm nodules to large cauliflower like growths
Distinct property of parvoviruses
Infection leads to large intranuclear inclusion bodies
Other name for Porcine Parvovirus infection
SMEDI (Stillbirth, Mummification, Embryonic Death, Infertility)
Viruses that have a preference for rapidly dividing (cycling) cells or cells in the S phase of development
Porcine parvovirus
Feline panleukomia virus
Canine parvovirus
Characteristic clinical signs of canine parvovirus
Panleukopenia
Enteritis
Myocarditis
Examples of virus that has hemagglutinin properties
Feline panleukopenia virus
Canine parvovirus
Adenovirus
Distinct characteristic of Adenoviruses
Enveloped helical virion with fibers projecting from the vertices
Diseases caused by members of Adenoviridae
-Infectious canine hepatitis (ICH)
-Egg drop syndrome (EDS)
An avian disease where in the site of tropism is in the shell gland region of the oviduct resulting to soft egg shells, where the chickens are apparently healthy
Egg Drop Syndrome
Largest and most complex of all viruses of vertebrate
Poxvirus
A brick shaped virion which can survive for many years in dry scabs
Orthopoxyirus
