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Viral Respiratory Infections Flashcards

1
Q

mechanisms used by respiratory tract pathogens to initiate disease

A

sufficient number of virus inhaled or acquired by direct contact

infectious particles are often airborne

infectious virus must remain alive and viable during transmission

virus must be deposited on susceptible tissue in the host

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2
Q

general approaches to prevention/treatment of respiratoory infections

A

genetically engineered or selected vaccines

passive antibodies - humanized, pooled, or human monoclonals

drugs against virus specific proteins or enzymes

hand washing - avoiding close contact

supportive care

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3
Q

orthomyxovirus

A

influenza A, B, and C

A infects both humans and animals

B and C only infect humans

influenza A most important - associated with epidemics and pandemics

particles are highly pleiomorphic - mostly pspherical or ovoid

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4
Q

components of the influenza A virion

A

host derived lipid bilayer that includes hemagglutinin (HA) and neuraminidase (NA)

inner shell is composed of matrix protein (M1)

nucleocapsid contains viral genome with eight unique segments, all are required to be infectious

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5
Q

H antigen

A

hemagglutinin

required for binding the influenza virus to the host cell

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6
Q

N antigen

A

neuraminidase

helps the mature virus escape from the cell

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7
Q

Describe the replication cycle of influenza.

A

Influenza binds to surface, endocytosed

Channel protein allows acidification of the vurlent particle

Release of genome into cell

Genome made in nucleus, transport into cytoplasm

Virus assembled and released

Two key steps - acidification step and the neuraminidase release step

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8
Q

classification of influenza

A

three types of H antigen

two types of N antigen

different combinations make different viruses

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9
Q

antigenic drift

A

changes in the discrete highly variable domains of the viral proteins through random mutations

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10
Q

antigenic shift

A

dramatic changes in virus by reassortment with another influenza virus

animals serve as a pool and where reassortment occurs due too infection with both animal and human viruses

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11
Q

epidemic flue

A

cyclic and usually caused by type B or type A

type A occur every 2 to 3 years, and type B occurs every 4 to 6 years

overall mortality rate is 1%

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12
Q

route and spread of influenza infection

A

entry via respiratory tract through inhalation

viral infection and spread is normally lmited to the epithelial cells of the respiratory tract

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13
Q

influenza pathogenesis

A

infects primarily upper and lower respiratory tract

influx of macrophages and lymphocytes

spectrum of disease ranges from asymptomatic infection to primary viral pneumonia

release of IL1 triggers fiver

release of interferon triggers aches and pains

humoral response is important for the control of these infections

replication of the virus causes desquamationof the ciliated epithelium, hyperplasia of transitoral cells, and increased secretions

inbucation time is 1 to 3 days

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14
Q

prevention/treatment of influenza

A

vaccinate those who are at risk

vaccines made from reassortment of egg-adapted strains that are then formalin inactivated

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15
Q

M2 protein

A

influenza protein channel that allows acidification for uncoating of the virus

permits flow of ions from the endosome into the virion center to disrupt interactions and release the viral genome

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16
Q

amantadine and rimantadine

A

drugs active against influenza A viruses

target is the M2 protein

prevents uncoating of the virus

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17
Q

Relenza and Tamiflu (oseltamivir phosphate)

A

neuraminidase inhibitor

block the cleavage of sialic acid and prevent virus from budding out of the host cell and infecting other cells

relenza must be inhaled

18
Q

syndromes potentially caused by influenza virus

A

uncomplicated rhinotracheitis

respiratory viral infection followed by bacterial pneumonia

viral pneumonia

usually rapid onset pneumonia

19
Q

coronaviruses

A

~13 species in the family

infect not only humans but also cattle, pigs, rodents, cats, dogs, and birds

an example would be SARS

20
Q

coronavirus morphology

A

particles are irregulalry-shaped

~60-220nm in diameter

outer envelope bearing distinctive “club-shaped” proteins

21
Q

pathogenesis of coronaviruses

A

can cause respiratory infections, enteric infections, and neurologic syndromes

transmitted by aerosols of respiratory secretions

growth appears to be localize din the epithelium of URT

most infections cause a mild, self-limited disease

greatest incidence in children, less common in adults

reinfections appear to occur

immunization may be difficult

22
Q

Severe Acute Respiratory Syndrome (SARS)

A

a respiratory illness caused by a coronavirus

civets and ferrets harbor this virus

symptoms include cough, shortness of breath, difficult breathing

severe virus capable of causing death

23
Q

MERS virus

A

coronavirus that went from bats to humans through camels

24
Q

paramyxovirus

A

family divided into three genera - paramyxovirus, pneumovirus, and morbillivirus

25
parainfluenzavirus 1-4
a type of paramyxovirus that causes an acute respiratory disease can cause mild influenza-like illness as well as bronchitis, croup, and pneumonia common infection of children transmitted by aerosols, usually limited to URT infections of LRT lead to more serious symptoms little serological variation, rare in adults
26
pneumovirus
a genera of paramyxovirus that includes respiratory syncytial virus (RSV)
27
morbillivirus
a genera of paramyxovirus that includes measles and canine distemper virus
28
mumps
humans are the only natural reservoir transmission through saliva and respiratory secretions typically causes painful swelling of parotid glands 16-18 days after infection preceded by primary replication of the virus in epithelial cells of the URT and local lymph nodes self-limited in children, but in adults a proportion of cases have other symptoms such as orchitis, meningitis, encephalitis, pancreatitis, myocarditis, nephritis
29
mumps prevention
one invariant serotype vaccines are available both formalin-inactivated and live attenuated exist latter is widely used
30
measles
one of the most infectious diseases known after a 10-12 day incubation period, dry cough, sore throat, conjunctivitis rad rash and Koplik spots a few days later complications include bronchopneumonia and otitis media and encephalitis subacute schlerosing pan encephalitis results form a rare strain
31
prevention of measles
both live and killed vaccines exist trivalent live attenuated vaccine (MMR) usually given virus best avoided during pregnancy
32
RSV
major cause of LRT disease in infants and young children highly infectious, transmission by respiratory secretions primary multiplication occurs in epithelial cells of URT, producing a mild illness in ~50% of children less than 8 months old, virus subsequently spreads into the LRT, causing bronchitis, pneumonia, and croup currently no vaccine infection does not result in lasting protection, so there can be repeated infections throghout life
33
treatment of RSV
**ribavirin** is used effectiveness is not ensured Respigram or Palivizumab are new drugs for prevention
34
picornaviruses
among the most diverse genomic RNA is infectious translates a large polyprotein
35
Coxackievirus
a subgroup of picornavirus classified as an enterovirus seasonal, epidemic pattern of infection mostly sub-clinical can be associated with meningitis, paralysis, and myocarditis
36
rhinovirus
a subgroup of the picornaviruses ~105 serotypes, repeated infections optimum growth temperature of 33 degrees C, good for URT infection symptoms due to damage to ciliated epithelium in URT can predispose to secondary bacterial infections no effective prophylaxis or treatment little or no cross-protection between serotypes
37
adenovirus
frequent cause of acute URT infections infections are common, most people have been infected by at least 1 type by age 15 commonly associated with a variety of clinical syndromes - little morbidity associated with infection
38
diseases associated with adenoviruses
acute respiratory illness pharyngitis gastro-enteritis conjunctivitis pneumonia keratoconjunctivitis acute hemorrhagic cystitis hepatitis
39
adenovirus morphology
non-enveloped, 60-90nm in diameter icosahedral symmetry easily visible in the electron microscope by negative staining thin glycoprotein fiber (IV) protrudes from the center of each penton
40
adenovirus prevention
no treatment options available inactivated or attentuated vaccines have been developed recent interest in gene therapy using adenoviruses for therapeutic purposes because the genome is easily manipulated in vitro
41
reovirus
produce minor upper respiratory tract infectiosn and gastrointestinal disease
42
hantavirus
infections caused by inhaling the virus contained in dried derr mouse (rodents) saliva, urine, or feces may evolve into a fatal disease characterized by respiratory insufficiency hantavirus pulmonary syndrome (HPS) characterized by an initial fever followed by the abrupt onset of acute pulmonary edema and shock

Pulmonary (37 decks)

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