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PID > Virology > Flashcards

Virology Flashcards

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
Q

Prevention of Viral diseases

A

Vaccination
Proper hygiene and sanitation
Eliminating Arthropod vectors
Quarantine and culling

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26
Q

Pathogenicity

A

The ability of a virus to cause disease in host (I.e. Harm the host)

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27
Q

Pathogen

A

Virus which causes disease

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28
Q

Pathogenesis

A

Manner/mechanism of development of disease

29
Q

Non-pathogenic

A

No disease- no clinical signs

30
Q

Virulence

A

A quantitative or relative measure if the degree of pathogenicity of the infecting virus

31
Q

Avirulent

A

Not virulent (not harmful to the host)

32
Q

Virulence variables

A

Factors related to Virus, Host, and other

33
Q

Factors related to virus

A 
Genetic variation of virus
Route of entry of virus in Host
Affinity of virus to host organs
Dose of infection
Immuno evasion
34
Q

Factors related to Host

A

Host species
Host Immunity
Host physiological factors (nutritional status, age, hormonal factors, stage of cell differentiation)
Fever

35
Q

Factors related to other

A

Environmental

Dual infections

36
Q

Measuring virulence: Lethal dose 50

A

The dose of virus required to cause death in 50% of animals

Lower L50 is more virulent

37
Q

Routes of entry: Skin

A 
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
Q

Routes of entry: Mucous membrane

A

Conjuctiva
oropharynx
Genitourinary Tract rectum
Defenses: IgA (antibodies), virucidal proteins

39
Q

Routes of entry: GI tract

A

Virus in contaminated food and water

40
Q

Routes of entry: respiratory tract

A

…

41
Q

Virus spread in host: epithelium

A

Local spread of virus on epithelial surfaces
Causes localized infection
May or may not proceed to subepithelial layer/underlying tissues

42
Q

Virus spread in host: epithelial surfaces

A

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
Q

Virus spread in host: subepithelial

A

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
Q

Virus spread in host: blood

A

To blood stream and then spread via blood stream

45
Q

Viremia

A

Presence of virus in blood

46
Q

Primary viremia

A

initial entry of virus into the blood

47
Q

Secondary viremia

A

Virus has replicated/multiplied in major organs and once more entered the circulation

48
Q

Disseminated Infection

A

Infection spreads beyond the primary site of infection

49
Q

Systemic infection

A

If a number of organs or tissues are infected

50
Q

Spread via nerves

A

Through peripheral nerves
Through receptor neurons in the nasal olfactory epithelium
Central nervous system
Virus can cross BBB and infect CNS

51
Q

Neurotropic Virus

A

Viruses that can infect neural cells.

Infection may occur by neural or hematogenous spread

52
Q

Neuroinvasive Virus

A

Viruses that enter the CNS after infection of a peripheral site

53
Q

Neurovirulent Virus

A

Viruses that cause disease of nervous tissue, manifested by neurological symptoms and often death

54
Q

Tropism

A

The specificity/affinity of a virus for a particular host tissue

55
Q

Pantropic virus

A

Can replicate in more than one host Organ/tissue

56
Q

Outcomes of viral injury

A 
Cell lysis
Apoptosis
Oncovirus
Persistant infection
Immunosupression
57
Q

Cell Lysis

A

following virus replication allowing release of new viruses

58
Q

Apoptosis

A

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
Q

Oncoviruses

A

Some virus can cause cancer and are known as oncoviruses or oncogenic viruses

60
Q

Persistent infection

A

Some viruses do not cause immediate death of infected host cells bi cause persistent infection

61
Q

Shedding

A

Of infectious virions is crucial to the maintenance of infection in populations

62
Q

Acute infection

A

Usually intensive shedding over short time period

63
Q

Persistent infection (shedding)

A

Can be shed at low titers for months to years

64
Q

Skin injury

A

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
Q

Injury to GI tract

A

Ingestion or from blood, systemic infection
destruction of intestinal enterocytes
GI disease, malabsorption, diarrhea
Pronounced dehydration, acidosis, hemoconcentration

66
Q

Respiratory Tract injury

A

gasping, respiratory distress from inflammed nervous tissue

67
Q

CNS injury

A

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
Q

Hemopoietic Injury

A 
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
Q

Viral infection of fetus

A

Teratogenic viruses: cause developmental defects of embryo of fetus after in-utero infection

PID (14 decks)

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