Bailey & Scott's Diagnostic Microbiology: Virology Flashcards


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1

virus

most abundant infectious agents on earth; obligate intracellular parasites; ultramicroscopic; not a living organism-use host to survive and replicate

2

classification

based on structure, chemical composition, and genetic makeup

3

International Committee on Taxonomy of Viruses

virology division of International Union of Microbiological Societies

4

virales

ending of the 14 orders

5

viridae

ending of the 150 families of viruses

6

virinae

ending of the 79 (of 150 families) subfamilies of viruses

7

virus

ending of the 1019 genera of viruses

8

polythetic

molecular sibblings; the 5560 problematic species of viruses

9

enveloped

has a covering around the viral particle that makes it less susceptible to environmental factors; protect nucleic acid and assist in attachment

10

retrovirus

with the help of retrogene, virus starts as RNA and becomes DNA through reverse transcriptase (ssRNA -> ssDNA -> dsDNA); allows for nuclear transcription and cytoplasmic translation; HIV, HTLV, and oncoviruses (cancer causing viruses)

11

capsids

protein coats that enclose and protect nucleic acid

12

complex

virus has capsid-like dense layer of lipoproteins that can act as a capsid

13

capsomers

protein building blocks of capsid

14

nucleocapsid

capsid together with nucleic acid

15

naked virus

containing no envelope- capsid proteins used to bind to cells

16

spikes

attachment proteins on outside of the envelope-has specificity and allows entry into host cell for replication

17

complex viruses

poxivirus, a large DNA virus; flexible-tailed bacteriophage

18

enveloped viruses with helical nucleocapsid

mumps and rhabdovirus

19

icosahedral nucleocapsid

herpesvirus and HIV/AIDS

20

helical capsid

plum poxvirus

21

icosahedral capsid

poliovirus and papilloma virus

22

DNA viruses

usually ds form but can be ss structure; circular or linear; replicated in host cell nucleus

23

RNA viruses

usually ss form, rarely ds form or segmented; replicated in host cell cytoplasm

24

positive-sense RNA

ssRNA ready for translation

25

negative-sense RNA

ssRNA that needs converted to be ready for translation

26

polymerase

enzyme required to replicate

27

replicase

enzyme that copies RNA

28

reverse transcriptase

enzyme that creates DNA from RNA

29

attachment/adsorption

life cycle phase that requires spikes, capsid, and envelopes

30

penetration

life cycle phase that phagocytoses cells by endocytosis, injects nucleic acid into cell, and fuses envelope

31

uncoating

life cycle phase noted by removal of viral capsid, release of nucleic acid to replicate

32

host range

spectrum of cells a virus can infect; example: HIV-T cells

33

tropism

tissue specificity of a virus

34

lytic viral replication

phage attaches to host cell, penetrates and injects DNA, synthesizes components, assemble into virions, and host cell lyses for new virions to be released

35

lysogenic cycle

phage attaches to host cell and injects DNA, circulates and integrates within bacterial chromosome by recombination becoming prophage, bacterium produce normally and prophage excise from bacterial chromosome by another recombination event

36

transduction

prophage exists in galactose-using host, phage genome excises carrying gal gene from host, then matures and cell lyses releases phage carrying gal gene, infects cell that cannot utilize galactose, becomes integrated into host DNA, and lysogeneic cell metabolizes galactose

37

budding

releases virus by exocytosis; nucleocapsid binds to membrane which pinches off and sheds viruses gradually; cell is not immediately destroyed

38

lysis

nonenveloped and complex viruses released when cell dies and ruptures

39

cytopathic effect

damage to host cells include lysis, inclusion bodies, change in size and shape of cells, and syncitia (multinucleated cells)

40

alteration of DNA

causes damage to host cells through transformation- oncoviruses

41

viral transport media

Hanks balanced salt solution with antibiotics; protects the cell in order to protect the virus within the cell; also filtered in order to eliminate bacteria

42

direct detection methods

testing includes electron microscopy, Tzanck prep, immunofluorescence, enzyme immunoassay for antigen, and molecular methods

43

electron microscopy

original viral testing method; not used now except for research; low sensitivity; requires experienced observer

44

Tzanck prep

stain cells from base of skin vesicle and examine for multinucleated giant cells; used for VZV and HSV; Giemsa stain, papanicolaou (Pap), and FA

45

direct fluorescent antibody stain

collect cells from base of fresh lesion, stain with specific antibody, and observe for fluorescence; more sensitive and specific; HSV and VZV

46

enzyme immunoassay

antigen/antibody complex formed and then bound to color producing substrate; liquid/well and membrane forms

47

molecular target DNA/RNA amplification

rapid, sensitive and specific for numerous viruses; specific sequences; new gold standard; tests of diagnosis, not useful for determining cure due to shedding virus

48

molecular signal amplification

not as prone to contamination and is quick, but not as sensitive as target amplification

49

viral cell culture

historical method, can take weeks to grow; three types of cell lines; inner tube wall coated with monolayer of cells plus liquid growth media for rapid cell growth

50

primary cell culture

direct from animal or human organ into culture tube subculture once; usually kidney cells, subculture once

51

diploid (semi continuous) cell culture

prepared from animal tissues; terminally differentiated, post-mitotic, usually fibroblasts from lung or foreskin; limited 20-50 passages

52

continuous cell culture

derived from tumors or mutagenic treatment of primary cell culture, can survive continuous passage into new vials

53

cytopathic effect

indicated by dead or dying cells for pattern of destruction specific to each virus

54

shell vial culture

speed up virus detection; cell monolayer on coverslip/vial and inoculated into vial and incubated; direct fluorescent antibody stain of coverslip to target early viral antigens

55

hemadsorption test

performed since some viruses agglutinate RBCs - measles, mumps, and influenza

56

primary infection

4-fold rise titer of IgG or total antibody between acute and convalescent sera; IgM present, single high titer of IgG

57

reinfection

>4-fold rise in titer of IgG or total antibody between acute and convalescent sera; absence or slight increase in IgM

58

serological markers

used for immunity titers and screening for infection

59

DNA viruses

includes adenoviridae, hepadnaviridae, herpesviridae, papillomaviridae, parvoviridae, polyomaviridae, and poxviridae

60

parvovirus

only DNA virus that is single stranded

61

enveloped DNA viruses

includes poxvirus, herpesviruses, and hepadnaviruses

62

nonenveloped DNA viruses

adenovirus, papillomavirus, polyomavirus, parvovirus

63

poxviruses

enveloped, largest and most complex animal viruses, have largest genome; multiply in cytoplasm in factory areas; epidermal cells and subcutaneous connective tissues; includes monkeypox

64

herpesviruses

includes HSV 1 and 2, VZV, CMV, EBV, and HHV 6, 7, and 8

65

smallpox

includes Hepatitis B

66

variola major

progressive eruptive lesions becoming pox pustules; exposed through inhalation or skin contact; leads to fever, malaise, prostration, and rash; first disease eliminated by vaccination

67

variola minor

less virulent smallpox

68

Molluscum contagiosum

non-sexual virus contagious by direct contact and fomites, STD virus lesions are small, smooth macules in genital area and thighs; AIDS patients have atypical form; can be frozen, cauterized, or removed by chemicals

69

Poxviruses

has many mamallian groups; monkeypox and cowpox most common in humans

70

monkeypox

one type of poxvirus; skin pocks, fever, swollen lymph nodes; number and severity of cases are increasing in Africa

71

cowpox

type of poxvirus; rare, usually confined to hands; other cutaneous sites can be involved

72

herpesviruses

large enveloped icosahedral dsDNA virus; replicates within the nucleus; large family with 8 that infect humans; all show latency and cause recurrent infection; latency occurs within small numbers of specific cells; clinical complications more severe with compromised immune system; common and serious among AIDS patients

73

HSV-1

oropharyngeal lesions on oropharynx; cold sores, fever blisters; latency in trigeminal ganglion; transmission by direct exposure to secretions and active lesions

74

HSV-2

oral and genital lesions; sexually transmitted by direct exposure to secretions and active lesions; latency primarily in sacral ganglia

75

HSV-1 infections

Herpes labialis, gingivostomatitis, and keratitis

76

Herpes labialis

most common recurrent HSV-1 infection; vesicles occur on lips or adjacent and crust over within 2-3 days

77

Herpetic gingivostomatitis

HSV-1, oropharynx in young children; infects gums; fever, sore throat, swollen lymph nodes

78

Herpetic keratitis

HSV-1, inflammation of the eye, conjunctivitis, and sensitivity to light

79

HSV-2 Herpes simplex

genital herpes; bilateral swelling and tenderness in the groin; clusters of sensitive vesicles on genitalia; urethritis, dysuria, cervicitis, vesicles ulcerate; recurrence less severe, triggered by stress

80

Herpetic whitlow

HSV-1 or 2 can penetrate a break in skin and cause localized infection; usually on finger; extremely painful and itchy

81

HSV-1 encephalitis

rare complication but most common sporadic form of viral encephalitis in US; usually underlying immunodeficiency

82

HSV

scrapings of infected lesions cultured, EIA, FA, PCR for diagnosis; treatment topical medications and antivirals

83

Varicella-zoster virus

humans only natural host; transmitted by respiratory droplets and contact; 2-week incubation; primary infection is chicken pox; characteristic vesicles; virus enters neurons and remains latent; reactivation results in shingles

84

cytomegalovirus

produce giant cells with nuclear and cytoplasmic inclusions; transmitted in saliva, respiratory mucus, breast milk, urine, semen, and cervical secretions; commonly latent in various tissues; asymptomatic to minor-mono like symptoms; pathogenic in immunocompromised; lifelong latent

85

molecular

preferred diagnosis of CMV to diagnose and monitor and treat appropriately

86

Epstein-Barr Virus

ubiquitous; affects lymphoid tissue and salivary glands; direct or oral contact; college-age population most vulnerable; immune deficient highly susceptible; sore throat, high fever, cervical lymphadenopathy; dormancy in B cells, reactivated, may be asymptomatic; lymphocytosis, neutropenia, and large atypical lymphs on differential; diagnosed by molecular methods

87

Burkitt lymphoma

B cell malignancy complication of EBV; develops in jaw grossly swells the cheek; central African children 4-8 years old

88

Nasopharyngeal carcinoma

complication of EBV; malignancy of epithelial cells; older Chinese and African men

89

Human herpes virus 6- Human B-lymphotropic virus

transmitted by close contact with saliva and other secretions; very common

90

Roseola

herpesvirus; acute febrile disease in babies 2-12 months; begins with fever followed by faint maculopapular rash; usually self-limited

91

HHV-7

closely related to HHV-6; similar scope of disease

92

HHV-8

herpesvirus associated with Kaposi's sarcoma; linked with common tumor of AIDS patients

93

Hepadnavirus

enveloped DNA viruses; never grown in tissue culture; unusual genome; tropism for liver; Hepatitis B

94

hepatitis

an inflammatory disease of liver cells that may result from several viruses; interferes with liver's excretion of bile pigments, bilirubin accumulates in blood and tissues causing jaundice

95

Hepatitis B

partially double stranded DNA, enveloped virus; transmission by direct contact with infectious blood or body fluids; usual hepatitis symptoms along with joint pain and rash; can be chronic-remains after acute infection resolves, can be reactivated; core antigen can reappear in serum; envelope antigen and viral DNA active replication

96

Hepatitis D

co-infective Hepatitis B; circular single-stranded RNA with rod-like shape; uses envelope proteins of Hepatitis B to replicate

97

Non-enveloped DNA viruses

Adenovirus, Papillomavirus, Polyomavirus, Parvovirus

98

Adenovirus

non-enveloped dsDNA virus; 30 types infect humans; infect lymphoid tissue, respiratory and intestinal epithelia and conjunctiva; oncogenic in animals; spread by respiratory and ocular secretions causing cold, pharyngitis, conjunctivitis, keratoconjunctivitis, acute hemorrhagic cystitis; severe treated with interferon

99

papilloma and polyoma viruses

small, nonenveloped dsDNA, circular DNA, cause persistent infections and tumors

100

human papillomavirus

caused by 100 different strains; transmissible through direct contact or contaminated fomites; incubation 2 weeks to more than a year; most common warts regress over time; can be chemically or surgically removed, cauterized, or frozen and can recur

101

papilloma

squamous epithelial growth, wart, or verruca

102

common seed warts

painless elevated rough growth on fingers

103

plantar warts

deep painful warts on soles of feet

104

genital warts- Condylomata acuminata

most common STD in US; ranges from tiny flat inconspicuous to extensive branching cauliflower-like masses; associated with cervical cancer

105

Polyomaviruses

JC and BK viruses; common throughout the world; majority asymptomatic or mild

106

JC virus

polyomavirus; progressive multifocal leukoencephalopathy uncommon fatal infection

107

BK virus

polyomavirus; infection in renal transplants cause complications in urinary function

108

parvovirus

nonenveloped ssDNA; small diameter and genome size; causes distemper in cats, enteric disease in dogs, fatal cardiac infection in puppies; few cause infections in humans

109

Parvovirus B19- Erthyema infectiosum (fifth disease)

children develop fever and rash on cheeks; severe fatal anemia results in fetus

110

Adeno-associated virus

defective parvovirus; cannot replicate without adenovirus

111

RNA viruses

Arenaviridae, Bunyaviridae, Caliciviridae, Coronaviridae, Filoviridae, Flaviviridae, Orthomyxoviridae, Paramyxoviridae, Picoviridae, Reoviridae, Retroviridae, Rhabdoviridae, and Togaviridae

112

Segmented genome single stranded enveloped RNA viruses

Orthoviruses (influenza), Bunyaviruses (Hantavirus), and Arenaviruses (California encephalitis)

113

Nonsegmented single stranded enveloped RNA viruses

Paramoxyviruses (measles and mumps), Rhabdovirus (rabies), Filiviruses (Ebola), Togaviruses (Rubella), Flaviviruses (Dengue fever), and Coronaviruses (SARS)

114

Single stranded enveloped RNA virus

retroviruses (AIDS) that encode reverse transcriptase

115

Singled stranded nonenveloped nonsegmented RNA viruses

Picornaviruses (Polio and Hepatitis A) and Calciviruses (Norwalk enteritis)

116

Double stranded nonenveloped RNA viruses

Reoviruses (Rotavirus diarrhea)

117

segmented

made up of multiple pieces of RNA instead of one strand

118

influenza

Orthomyxoviruses containing 3 various strains depending on spike proteins; A most common; attaches to and multiplies in cells of respiratory tract; segments enter nucleus; new viruses assembled and bud off cell

119

Hemagglutinin (H)

glycoprotein of influenza; 15 various subtypes; most important virulence factor; binds to host cell; undergo genetic changes decreasing effectiveness of host

120

Neuraminidase (N)

influenza glycoprotein; 9 subtypes; hydrolyzes mucus and assists viral budding and release; undergo genetic changes decreasing effectiveness of host immune response

121

antigenic drift

gradual change in amino acid composition-influenza mutation

122

antigenic shift

one of the genes or RNA strands is substituted with a gene or strand from another influenza virus from a different animal host-influenza mutation

123

Influenza B

only undergoes antigenic drift, not antigenic shift

124

Influenza C

known to cause only minor respiratory disease; probably not involved in epidemics

125

Influenza A

acute, highly contagious respiratory illness; seasonal; can cause pandemics; among top ten causes of death in US; binds to ciliated cells of respiratory mucosa causing rapid shedding of cells, stripping respiratory epithelium causing severe inflammation; leads to fever, headache, myalgia, sore throat, and cough; weakened host defenses predispose patients to secondary bacterial infections (Pneumonia)

126

Bunyaviruses and arenaviruses

transmitted zoonotically; cause periodic epidemics; extremely dangerous BL4 viruses

127

Bunyaviruses

transmitted by insects and ticks; California encephalitis, Rift valley fever, Korean hemorrhagic fever, American-hantavirus, Sin Nombre virus; dangerous BL4 virus

128

Arenaviruses

Lassa fever, Argentine hemorrhagic fever, Bolivian hemorrhagic fever, and Lymphocytic choriomeningitis; closely associated with rodent host; dangerous BL4 virus

129

Paramyxoviruses

includes parainfluenza and mumps, Morbillivirus (measles), Pneumovirus (RSV), and Metapneumovirus; respiratory transmission, envelope has glycoprotein and F spikes that initiate cell to cell fusion

130

Syncytium

fusion with neighboring cells, multinucleate giant cells form

131

Parainfluenza

widespread Paramyxovirus; more benign than influenza; respiratory transmission seen mostly in children leading to minor cold, bronchitis, bronchopneumonia, and croup

132

Mumps

epidemic parotitis Paramyxovirus; self limited associated with painful swelling of parotid salivary glands; humans are only reservoir; long-term immunity once infected; 300 cases per year; 2-3 week incubation; fever, muscle pain, malaise, classic swelling of one or both cheeks; symptomatic treatment; eradicated before dipshits stopped vaccinating their children

133

Measles-Rubeola

Morbillivirus; very contagious transmitted respiratory leads to rash, sore throat, high fever, cough, runny nose, red eyes, light sensitivity; pneumonia and can cause brain degeneration; humans only reservoir; less than 100 cases per year in US; frequent cause of death worldwide

134

subacture sclerosing panencephalitis (SSPE)

most serious measles complication; progressive neurological degeneration of sercerebral cortex, white matter, and brain stem; 1 case/million infections; involves defective virus spreading through brain by cell fusion and destroys cells; leads to coma and death in months or years

135

Respiratory Syncytial Virus (RSV)

pneumovirus that infects upper respiratory tract producing multinucleate cells; epithelia of nose and eye portal of entry and replicates in nasopharynx causing fever, rhinitis, pharyngitis, otitis, croup

136

Metapneumovirus

community acquired respiratory tract disease; prevalent during winter; most cases in less than 6 years of age; 2nd to RSV in cause of bronchiolitis; does not grow in culture

137

Rabies

rhabdovirus from genus lyssavirus; enveloped bullet-shaped virions; slow progressive zoonotic disease; primary reservoirs are wild mammals; enters through bites, scratches and inhalation of droplets and advances toward ganglia, spinal cord and brain, replicates in salivary glands; three phases from fever, and nonspecific flu-like symptoms (Prodromal), agitation and disorientation, fear of water (Furious), and paralyzation, coma (Dumb phase)

138

Negri bodies

intracellular inclusions in nervous tissue diagnostic of rabies

139

Coronaviruses

relatively large RNA viruses with distinctively spaced spikes on their envelopes; common in domestic animals; enteric and respiratory forms

140

Severe Acute Respiratory Syndrome (SARS)

worldwide outbreak in 2003 starting in China and spreading to 29 countries; transmitted through droplets or direct contact leading to fever, body aches, and malaise

141

SARS-CoV2

worldwide outbreak in 2019 beginning in Wuhan China; 4 mutations so far; transmitted through droplet or direct contact; symptoms vary- alpha-cough, loss of taste/smell, low O2; delta-more nasal/sinus with loss of taste/smell

142

Middle Eastern Respiratory Syndrome (MERS)

isolated to Arabian peninsula in 2012; direct contact with infected camels; close human to human contact spread infection; 30% fatality rate; fever, rhinorrhea, cough, malaise followed by SOB; EIA and PCR

143

Rubella-German measles

caused by Rubi virus, a type of Toga virus; endemic disease-eliminated from US in 2004; most adolescents and young adults; live attenuated virus that can cause miscarriage or birth defects so not vaccine during pregnancy; serology, CRS, Molecular methods

144

Hepatitis C

only blood-borne Flavivirus-2.4 million infected; acquired through blood contact-needles; chronic disease without overt symptoms and can lead to cancer; no vaccine; serology and molecular for diagnosis and monitoring; routine testing for 1945-1965, clotting factors before 1987 and organs and blood received before 1992, dialysis patients, HIV patients, positive mothers' children, and accidental needle sticks

145

Arboviruses

viruses spread by arthropod vectors-mosquitoes, ticks, flies, and gnats; 400 viruses caused by Togavirus, Flavivirus, Bunyavirus, and Reovirus; most are mild fevers, some can cause encephalitis and hemorrhagic fever

146

viral encephalitis

brain meninges and spinal cord infected by arbovirus infections leading to convulsions, tremors, death, permanent brain damage

147

yellow fever

rare arbovirus in US; urban-humans and mosquitoes, Savannah-Africa, and Sylvan-monkeys and mosquitoes of South America; typical flu-like symptoms; significant mortality rate

148

Dengue fever

arbovirus; 400 million people infected annually in tropics and subtropics; rare in US, but endemic in Puerto Rico, Latin America, SE Asia, and Pacific Islands; no vaccine; high fever and severe flu-like symptoms including difficulty breathing and GI symptoms such as vomiting blood, severe abdominal pain, and black, tarry stool; serology and PCR

149

Chikungunya virus

arbovirus; vector Aedes mosquito originating in Asia and Africa continents; Carribean and US with mosquito migration; acute febrile illness with rash followed by extreme joint pain, less fatalities than Dengue-no hemorrhagic phase; Sero and PCR

150

Zika virus

arbovirus; Vector Aedes mosquito common in South America-Brazil; mild form of Dengue; Sero and PCR

151

Filovirus

includes Ebola and Marburg

152

Ebola virus

type of Filovirus; >20 outbreaks since 1976; most recent in West Africa in 2013; prolonged due to area affected highly populated and medical limited; LRN labs only; direct contact with blood/body fluids; very high fatality; Marburg fruit bat; fever, weakness, myalgia, headache; EIA, PCR after four days

153

Marburg virus

rare cases of Filovirus; first recognized in 1967; direct contact with blood/body fluids; very high fatality; Marburg fruit bat; fever, weakness, myalgia, headache; EIA, PCR after four days

154

Human Immunodeficiency Virus (HIV)

retrovirus that replicates through reverse transcriptase; viral genes permanently integrated into host DNA; enters cell using CD4 as receptor and Tcells or macrophages as coreceptors and multiplies easily through reverse transcriptase since new strands are not proofread; many subtypes; enters through mucus membranes; does not survive long outside body; causes leukopenia, giant T cells, CD4 destruction; molecular best method

155

Picornaviruses

single stranded nonenveloped and nonsegmented; includes Enterovirus (Poliovirus and HAV), Rhinovirus, and Cardiovirus

156

Poliovirus

enterovirus of the Picornavirus; naked capsid; three types: 1-3; person to person transmission-raw or undercooked food or drinking water contaminated with infected feces; resistant to acid, bile, and detergents

157

Poliomyelitis (polio)

acute enteroviral infection picornavirus; affects spinal cord; can cause neuromuscular paralysis; transmission is fecal-oral; adhere to receptors of mucosal cells in oropharynx and intestine; multiply and shed in throat and feces, enter blood; most are short term and mild-fever, headache, nausea; more serious viremia leading to brain and spinal cord infection-muscle pain, spasm, meningeal inflammation, hypersensitivity

158

post polio syndrome

invasion of motor neurons causing flaccid paralysis leading to progressive muscle deterioration; most infected in childhood and syndrome occurs decades later

159

nonpolio enteroviruses

most common are coxsackieviruses A and B, Echoviruses, and Nonpolioenteroviruses; less virulent than polioviruses; respiratory infections and hand-foot-mouth; rarely cause paralysis, meningitis, encephalitis

160

Hepatitis A virus

cubical picornavirus resistant to heat and acid; acute instead of chronic; fecal-oral; multiplies into small intestine -> blood -> liver; flu like symptoms, no jaundice

161

Rhinovirus

more than 110 serotypes associated with common cold; unique molecular surface (no vaccine); contaminated hands; optimal 33 degrees; headaches, chills, fatigue, sore throat, cough, nasal drainage

162

Caliciviruses

Norovirus with 33 different genotypes; fecal-oral; 1/3 of all GI cases-nausea, vomiting, diarrhea, chills, cramps

163

Hepevirus

fecal oral; contaminated water, food, animals, not person to person; acute infection with high mortality in women

164

Reovirus

cold-like upper respiratory infection; enteritis

165

Rotavirus

Reovirus; fecal-oral; diarrhea in children; primary cause of mortality and morbidity-vaccine

166

prions

misfolded proteins that contain no nucleic acid; extremely resistant to sterilization; transmissible spongiform encephalopathies-fatal neurodegenerative diseases; scrapie in sheep and goats, bovine (mad cow) spongiform encephalopathies; Creutzfeldt-Jakob Syndrome

167

Creutzfeldt-Jakob disease

alteration in structure of normal protease resistant protein (PrP) protein found in brain into abnormal form that results in nerve cell death, spongiform damage, and severe loss of brain function; transmitted by direct or indirect contact with infected brain tissue or CSF

168

satellie viruses

dependent on other viruses for replication; adeno-associated-replicates only in cells infected with adenovirus, delta agent-naked strand RNA expressed only in presence of hepatitis B virus

169

Viroids

short pieces of RNA, no protein coat; only been identified in plants