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Virology Flashcards

(69 cards)

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1
Q

Virology

A

The study of viruses and viral diseases

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2
Q

Virus

A

Piece of bad news wrapped up in a protein

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3
Q

Virologist

A

Someone who studies viruses

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4
Q

Importance of Veterinary Virology

A

Viral diseases cause high rates of mortality and morbidity in animals and birds
Viral diseases can significantly impact food safety and security
Viral diseases can cause tremendous economic losses and are expensive to control and prevent
Zoonosis: most deadly viruses are animal viruses that transferred to humans

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5
Q

Zoonosis

A

Viral diseases can be transmitted form animals and birds to humans

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6
Q

Defining Viruses

A

Non-living entities
Contain nucleic acid genome (DNA or RNA) surrounded by a protein coat (capsid) and in some cases other layers of material, such as lipid envelope
Viruses do not possess standard cellular organelles such as mitochondria, etc.
Cannot make energy or proteins by themselves and have to rely on a host cell
Similar to obligate intracellular parasites. Outside the living cell, viruses are inert or dormant particles, whereas, inside the virus hijacks and utilizes the host cell machinery to produce its proteins and nucleic acid for the next generation of viruses
Do not have genetic capability to multiply by division, such as Binary Fission. The process of viral reproduction resembles an assembly line in which various parts of the virus come together from different parts of the host cell to form new virus particles

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7
Q

Virus Structure

A

DNA or RNA genes inside a capsid. Inside a envelop (bubble of fat) with molecules of protein

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8
Q

Capsid

A

The protein shell of a virus that encases.envelopes the viral nucleic acid or genome
Made up of capsomeres held together by non-covalent bonds

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9
Q

Nucleocapsid

A

Capsid + virus nucleic acid

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10
Q

Lipid envelope

A

Some viruses may have an additional layer known as envelope that covers the capsid
Usually a lipid bilayer derived form host cell
Glycoproteins are present on the surface of the envelope, and often appear as spikes

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11
Q

Pleomorphism

A

The ability of some virus to alter their shape or size

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12
Q

Ebola Virus

A

Filament shaped

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13
Q

Rabies Virus

A

Bullet shaped

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14
Q

Bacterophage

A

Tadpole shaped

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15
Q

Tobacco-mosaic virus

A

Rod-shaped

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16
Q

Poxvirus

A

Brick-shaped

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17
Q

Rotavirus

A

Spherical

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18
Q

Chemical composition of Viruses

A

Virus Nucleic acid can be either DNA or RNA and these can both be either double-stranded or single-stranded

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19
Q

Virus Replication

A

Attachment (lock and key specific)
Penetration (enters cell)
Uncoating ( come out of protein capsid coat)
Synthesis of Viral Nucleic acid and Protein ( hijack cell to get multiple copies)
Assembly and maturation (new capsid will fuse and mature)
Release in large numbers

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20
Q

Impacts of Virus replication in host cell

A

Cell Death: lysis (spread virus all over), alteration of cell membrane, apoptosis
No apparent changes to the infected cell, latent, persistent, or chronic infection
Transformation of cell to malignant one
Fusion of cells, Multinucleated

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21
Q

Viral Taxonomy: ICTV

A

International committee on taxonomy of viruses classification system is followed by virologists worldwide
THe ICTV is the only body charged by the international union of microbiological societies with the task of developing, refining, and maintaining a universal virus taxonomy

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22
Q

What is considered for classification of viruses

A

Nature of virus genome and virus genetic diversity
Virus replicating strategies
Virus morphology

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23
Q

Diagnosis/Detection

A

By gross evaluation and histopathology
By cultivation/isolation: cultivation/isolation of viruses in cells/tissue culture. Inoculation in eggs
Electron Microscopy (to identify and study the morphology of a virus)
Serology ( detection of viral antigen or host antibody against virus ELISA)
Detection of viral nucleic acids.molecular biology (RT-PCR)

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24
Q

Treatment

A

Antiviral drugs
Immune system stimulation: interferon therapy
Synthesis antibodies or administration of natural antiserum (antibodies)

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25
Prevention of Viral diseases
Vaccination Proper hygiene and sanitation Eliminating Arthropod vectors Quarantine and culling
26
Pathogenicity
The ability of a virus to cause disease in host (I.e. Harm the host)
27
Pathogen
Virus which causes disease
28
Pathogenesis
Manner/mechanism of development of disease
29
Non-pathogenic
No disease- no clinical signs
30
Virulence
A quantitative or relative measure if the degree of pathogenicity of the infecting virus
31
Avirulent
Not virulent (not harmful to the host)
32
Virulence variables
Factors related to Virus, Host, and other
33
Factors related to virus
``` Genetic variation of virus Route of entry of virus in Host Affinity of virus to host organs Dose of infection Immuno evasion ```
34
Factors related to Host
Host species Host Immunity Host physiological factors (nutritional status, age, hormonal factors, stage of cell differentiation) Fever
35
Factors related to other
Environmental | Dual infections
36
Measuring virulence: Lethal dose 50
The dose of virus required to cause death in 50% of animals | Lower L50 is more virulent
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Routes of entry: Skin
``` Cannot penetrate intact skin Cut or breach Transcutaneous injection 1. bite of arthropods (ticks, flea, mosquito) 2. Bite of infected animal (rabies) 3. Contaminated objects ```
38
Routes of entry: Mucous membrane
Conjuctiva oropharynx Genitourinary Tract rectum Defenses: IgA (antibodies), virucidal proteins
39
Routes of entry: GI tract
Virus in contaminated food and water
40
Routes of entry: respiratory tract
...
41
Virus spread in host: epithelium
Local spread of virus on epithelial surfaces Causes localized infection May or may not proceed to subepithelial layer/underlying tissues
42
Virus spread in host: epithelial surfaces
From local infection of epithelial surfaces Viruses may reach subepithelial layer/underlying tissues from epithelial surfaces To do this, viruses should overcome local host defense
43
Virus spread in host: subepithelial
To subepithelial invasion and lymphatic spread In subepithelial tissue, viruses get access to lymphatics, phagocytic cells and tissue fluids These may help carry virus to the blood stream
44
Virus spread in host: blood
To blood stream and then spread via blood stream
45
Viremia
Presence of virus in blood
46
Primary viremia
initial entry of virus into the blood
47
Secondary viremia
Virus has replicated/multiplied in major organs and once more entered the circulation
48
Disseminated Infection
Infection spreads beyond the primary site of infection
49
Systemic infection
If a number of organs or tissues are infected
50
Spread via nerves
Through peripheral nerves Through receptor neurons in the nasal olfactory epithelium Central nervous system Virus can cross BBB and infect CNS
51
Neurotropic Virus
Viruses that can infect neural cells. | Infection may occur by neural or hematogenous spread
52
Neuroinvasive Virus
Viruses that enter the CNS after infection of a peripheral site
53
Neurovirulent Virus
Viruses that cause disease of nervous tissue, manifested by neurological symptoms and often death
54
Tropism
The specificity/affinity of a virus for a particular host tissue
55
Pantropic virus
Can replicate in more than one host Organ/tissue
56
Outcomes of viral injury
``` Cell lysis Apoptosis Oncovirus Persistant infection Immunosupression ```
57
Cell Lysis
following virus replication allowing release of new viruses
58
Apoptosis
The process of programmed cell death, which is essentially a mechanism of cell suicide that the host activates as a last resort to eliminate viral factories before new virus production is complete Different from lysis where viral replication is complete, host cell is destroyed and new virions released
59
Oncoviruses
Some virus can cause cancer and are known as oncoviruses or oncogenic viruses
60
Persistent infection
Some viruses do not cause immediate death of infected host cells bi cause persistent infection
61
Shedding
Of infectious virions is crucial to the maintenance of infection in populations
62
Acute infection
Usually intensive shedding over short time period
63
Persistent infection (shedding)
Can be shed at low titers for months to years
64
Skin injury
can be localized (papilloma) or disseminated (lumpy skin disease) Vesicle: fluid filled sac, small distinct elevation Ulcer: opening in the skin caused by sloughing of necrotic tissue, extending pass the epidermis Nodule/tumor: palable, solid, elevated mass nodules with distinct borders. Tumors extending deep into the dermis (nodule is a solid tumorous mass) Warts: benign skin growths that appear when a virus infects the top layer of skin Erythema: reddening of skin
65
Injury to GI tract
Ingestion or from blood, systemic infection destruction of intestinal enterocytes GI disease, malabsorption, diarrhea Pronounced dehydration, acidosis, hemoconcentration
66
Respiratory Tract injury
gasping, respiratory distress from inflammed nervous tissue
67
CNS injury
Lytic (destruction/bursting) infections of neurons Neuronal necrosis (necrosis is death of body tissue) Neuronophagia (killing/devouring of neuronal cells by phagocytic cells) Pervascular cuffing (inflammatory cells around blood vessels in CNS) Progressive demyelination Neuronal vacuolation in prion disease
68
Hemopoietic Injury
``` Hemorrhages: petechiae hemorrhage (pin-point/small spots) Ecchymoses hemorrhage (larger areas of hemorrhage, ill-defined margins) Disseminated intravascular coagulation- clots are formed throughout the body followed by hemorrhages ```
69
Viral infection of fetus
Teratogenic viruses: cause developmental defects of embryo of fetus after in-utero infection

PID (14 decks)

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