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virology Flashcards

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Biology 101 flashcards
1
Q

size range of viruses

A

18 nm to 300 nm

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2
Q

families of DNA viruses (7)

A

1) poxviridae: smallpox virus, monkeypox virus
2) herpesviridae: herpes simplex virus (types 1 and 2), epstein-barr virus, cytomegalo virus, human herpes virus 6,7,8
3) adenoviridae - adenovirus
4) hepadnaviridae - hep B virus
5) polyoma viridae - BK virus
6) papilloma viridae - papilloma virus
7) parvoviridae - parovirus B19

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3
Q

capsids

A

protein; environmentally stable to temperature, acid, proteases, detergents drying; release from cell by lysis;

consequences: can be spread easily, can dry out and retain infectivity; can survive the adverse acidic conditions of the gut; antibody may be sufficient for immunoprotection

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4
Q

enveloped virus

A

membrane; lipid; proteinl glycoproteins

environmentally labile - is disrupted by acid, detergents, drying, heat; modifies cell membrane during replication; is released by budding and cell lysis

consequences: must stay wet; cannot survive the gastrointestinal tract; spreads in large droplets, secretions; does not need to kill the cell to spread; may need antibody and cell-mediated immune response for protection and control; elicits hypersensitivity and inflammation to cause immunopathogenesis

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5
Q

how do hemagglutin glycoprotein trimers of influenza virus help in the rapid infection of various human cell types?

A

sialic acid binding domain - attachment region of influenza virus binds to sialic acid domains expressed in various types of cells; this facilitates the binding of influenza with several cell types

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6
Q

how does the antibody molecules, nucleoside analogues and protease inhibitors help combat the spread of an infecting virus?

A

antibody - before entering the cell binds to viral proteins
nucleoside analogs - inhibit the replication, DNA synthesis
protease inhibitors - inhibit assembly of virus from a polyprotein segment

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7
Q

families of RNA viruses

A

1) paramyxoviridae - measles virus, mumps, virus, metapneumovirus
2) orthomyxoviridae - influenze virus types A, B, C
3) coronaviridae - coronavirus, SARS
4) rhabdoviridae - rabies virus
5) retrovirdiae - human T-cell leukemia virus types I and II< HIV
6) picornaviridae - poliovirus, hep A
7) togaviridae - rubella virus
8) flaviviridae - yellow fever virus, west nile virus, hep C

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8
Q

DNA viruses

A

DNA is not transient or labile
viral genomes remain in the infected cell
many DNA viruses establish persistent infecitons
DNA genomes reside in the nucleus
viral genome resembles host DNA for transcription and replication
viral genes must interact with host transcriptional machinery (except for pox viruses)
viral gene transcription is temporarily regulated (early genes and late genes)

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9
Q

RNA viruses

A 
RNA is labile and transient
replicate in the cytoplasm
cells cannot replicate RNA
RNA viruses must encode an RNA dependent RNA polymerase
prone to mutation
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10
Q

what are the probes as well as the material being tested during in situ hybridization?

A

DNA probes can be used to detect specific genetic sequences in biopsy specimens

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11
Q

what are the probes as well as the material being tested during northern blot?

A

DNA probe hybridization of RNA electrophoretically separated and blotted onto a nitrocellulose filter

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12
Q

what are the probes as well as the material being tested during southern blot?

A

DNA probe hybridization of DNA separated in gel electrophoresis and transferred onto a nitrocellulose paper

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13
Q

what are the probes as well as the material being tested during western blot hybridizations?

A

electropohoretically separated proteins can be identified using antibodies

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14
Q

what are the probes as well as the material being tested during PCR?

A

Amplified single copies of viral DNA millions of times over; can be used to detect even few viruses lying dormant in infected cells; most sensitive, recent and preffered method to detect a few DNA molecules

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15
Q

what are the probes as well as the material being tested during RT-PCR?

A

involves the use of revere transcriptase enzyme of retroviruses; viral RNAs are first converted to DNA by reverse transcriptase enzyme and then PCR amplified

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16
Q

Prodrome

A

non specific early symptoms

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17
Q

Tropism

A

a particular disease caused by several viruses that have a common tissue preference - hepatitis (liver), common cold (upper respiratory tract)

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18
Q

Viremia

A

presence of virus in the blood circulation

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19
Q

What are acyclovir and AZT? How do they influence the viral spread?

A

Acyclovir is a nucleoside analogues inhibit viral DNA polymerase selectively and there by inhibit viral DNA polymerase selectively and thereby inhibit viral replication

AZT was originally developed as anticancer drug. It si 100 fold more sensitive to viral reverse transcriptase than to the host cell DNA polymerase. AZT is the first useful therapy for HIV infection

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20
Q

some viruses do not cause any cytopathological effects (CPE) on tissues. How can these viruses be detected and identified?

A

cells infected with influenze virus, parainfluenza virus, mumps virus and togavirus do not exhibit classic CPEs; these cells expressive viral glycoprotein - hemagglutinin can bind to erythrocytes (hemadsorption) of a given species and cause hemagglutination; antibodies against specific viruses can prevent the hemagglutination caused by that specific viruses (against which the antibodies have been raised); this demonstration of hemagglutination and inhibition of hemagglutination is a major tool to detect and identify a specific virus without a CPE

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21
Q

What is a PFU?

A

plaque forming units

viruses can be quantitated by determining the greatest dilution that retains the following titers: TCD50, LD50, ID50

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22
Q

TCD50

A

tissue culture dose - titer of virus that cause cytopathologic effects in half the tissue

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23
Q

LD50

A

lethal dose; titer of virus that kills 50% of a set of test animals

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24
Q

ID50

A

infectious dose; titer of virus that initiates a detectable symptom, antibody or other response in 50% of a set of test animals

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25
Q

What are the methods of viral transformation and immortalization

A

viruses can cause cancer of the infected cells; this is achieved by removal of growth suppressors in host cells and enhancement of growth activators

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26
Q

What are the methods of viral transformation and immortalization

A

viruses can cause cancer of the infected cells; this is achieved by removal of growth suppressors in host cells and enhancement of growth activators

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27
Q

Why is HIV one of the deadliest viruses?

A

causes antigenic drift which helps the virus to escape the immune system; virus has tropism for CD4 expressing T cells and macrophages; can travel to lymph nodes and get in contact with CD 4 T cells

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28
Q

Gp120, Gp 41 and chemokine receptors: where are they located and what are their roles

A

they help the virus bind to the CD4 receptor; chemokine receptors (CXCR4) facilitate the binding and bring them closer to each other; enveloped spherical virion loses its envelope upon entering the cell; first a negative strand of DNA is synthesized by reverse transcriptase

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29
Q

poxviridae

A

smallpox virus, monkeypox virus

30
Q

herpesviridae

A

herpes simplex virus (types 1 and 2), epstein-barr virus, cytomegalo virus, human herpes virus 6,7,8

31
Q

adenoviridae

A

adenovirus

32
Q

hepadnaviridae

A

hep B virus

33
Q

polyoma viridae

A

BK virus

34
Q

papilloma viridae

A

papilloma virus

35
Q

parvoviridae

A

parovirus B19

36
Q

paramyxoviridae

A
  • measles virus, mumps, virus, metapneumovirus
37
Q

orthomyxoviridae

A

influenze virus types A, B, C

38
Q

coronaviridae

A

coronavirus, SARS

39
Q

rhabdoviridae

A

rabies virus

40
Q

retrovirdiae

A

human T-cell leukemia virus types I and II< HIV

41
Q

picornaviridae

A

poliovirus, hep A

42
Q

togaviridae

A

rubella virus

43
Q

flaviviridae

A

yellow fever virus, west nile virus, hep C

44
Q

how does herpes virus manage to stay latent after infecting a human being?

A

trigeminal ganglia

45
Q

distinguish between HSV1 and HSV2 in terms of the tergion of infection in a human body.

A

HSV-1 causes syndromes mainly in the upper part of the body

HSV-2 causes syndromes in the genital area

46
Q

what are the diseases caused by HSV1, HSV2, HSV3, and HSV4?

A

HSV1 or HSV2 can cause primary herpes gingiovostamatitis

HSV3 - vericella-zoster virus - chicken pox/ shingles

HSV4 - epstein-barr virus

47
Q

what organs of a human body are infected by varicella (HSV3) virus during primary and secondary viremia?

A

primary viremia - viral replication in the regional lymph nodes

secondary viremia - virla replicationin the spleen, liver, and other organs –> infection of skin and appearance of vesicular rash

48
Q

after infecting a human being, varicella virus goes through the stages of incubation, primary viremia and secondary viremia. At what stage of infection the virus becomes contagious and cause fever?

A

secondary viremia - day 10

49
Q

Zanamavir, Oseltamivir, Amatadine and Rimantadine have antiviral effect. How do they bring about this inhibitory effect on influenza A virus infeciton.

A

zanamavir and oseltamivir inhibit neuraminidase of influenza A and B

amantadine and rimantadine inhibit uncoating step in influenza A infection

50
Q

Herpes infection causes the following diseases: herpes zoster, herpes labialis, herpes whitlow and herpes gladiatorium. Which of these diseases occurs in nurses and physicians attending patients with HSV INFECTION?

A

Herpes whitlow occurs in nurses and physicians attending patients with HSV infections

51
Q

which one of the influenza viruses can cause pandemics? what organ systems are affected by this virus infection?

A

influenza A

52
Q

describe the structure of influenza virus A, B, and C with respect to envelop and genetic material.

A

influenza A, B, and C are enveloped and have a negative sense RNA genome

53
Q

name the viruses that can cause cervical cancer

A

papillomaviruses and polyomaviruses

54
Q

names the virus that can cause kerantinization of epithelial cells

A

papillomavirus

55
Q

name the virus that causes molluscum contagiosum

A

poxviruses

56
Q

name the virus that causes small pox

A

poxviruses

57
Q

describe the method by which live vaccinia virus with recombinant DNA can be produced. Why this vaccination was discontinued?

A

vaccinia live form vaccination was abandoned due to fatalities caused in spite of being effective against small pox; altered vaccinia is being used as expression vector

58
Q

describe conjunctivitis

A

caused by adenovirus

59
Q

describe molluscum contagiosum

A

infection by pox virus contianing double stranded linear DNA genome which replicates in cytoplasm; lesions nodular to wartlike; contains pearl-like umbilicated nodule; nodule has a central casious plug that can be squeeze out

60
Q

describe erythema infectiosum

A

caused by parovirus B19; infected children have flu like illness (fever, muscle pain, tired); after a few days of flu suddently develops an intensely red rashon cheeks and trunk

61
Q

which is the largest and most complex of all the viruses

A

pox viruses - contain linear double stranded genome; DNA viruses replicate in the cytoplasm; include human viruses variola (small pox) and molluscum contagiosum

62
Q

explain the following with a mention of the associated viruses

a. dead and infection
b. herpangina
c. hand-foot and mouth disease
d. genetic assortment
e. epidemic
f. pandemic

A

dead end infection - alphavirus and flavivirus - no transmission of the virus back to the vector

63
Q

describe the genome and the characteristic features of corona virus and rhino virus

A

corona virus - enveloped virus; contains long positive RNA genome; early phase of translation - RNA dependent RNA pol; late phase - produce structural and non structural proteins

64
Q

what are the symptom and diseases resulting from the infection of coxsackie virus

A

infectious disease in children; characterized by a sunnder occurence of fever, loss of appetite, inflammation and ulceration of throat; distinct vesicles on the palate

vesicular lesions on the hands, feet, mouth and tongue; first develops in the oral cavity; within one day spreads to other parts

65
Q

what are the symptom and diseases resulting from the infection of paramyxovirus

A

measles, mumps, and parainfluenza virus; virus induce cell-cell fusion causing multinucleated giant cells; transmitted in respiratory droplets and initiate in the respiratory tract; cell-mediated immunity causes may of the symptoms but essential for control of the infection

66
Q

what are the symptom and diseases resulting from the infection of alpha virus

A

DHF - deng hemorrhagic fever (loss of fluids from vasculature)
DSS - deng shock syndrome

67
Q

what are the symptom and diseases resulting from the infection of rubella virus

A

rubella enters and infects the nasopharynx and lung; spreads to the lymph nodes and monocyte macrophage system; circulating antibody can block the transfer of the virus; immunologically deficient pregnant woman, the virus can infect the placenta and spread to the fetus; can cause serious congenital abnormalities in the chidl

68
Q

what are the symptom and diseases resulting from the infection of corona virus

A

second most prevalent cause of the common cold; prefers to prolerate in upper respiratory tract; in 2002, SARS (atypical pneumona characterized by high fever, chills, headache, dizziness, myalgia and breathing difficulty; symptoms develop within 10 days of exposure to person or place associated with SARS; infected human beins from animals)

69
Q

which virus is being used for vaccination as a live attenuated form?

A

paramyxovirus

70
Q

name the virus that gets transmitted through arthropods

A

togaviruses (alpha viruses, rubiviruses)
flaviviruses (west nile virus)
arbovirus (alpha virus and flavivirus)

Microbiology (15 decks)

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