Viral Infections Flashcards
1
Q
Latency
A
cell infected with a virus that does not interfere with cellular functions - virus can emerge to produce disease years after the primary infection
2
Q
RNA Viruses vs DNA Viruses
A
- RNA viruses (HIV-1, hepatitis C) have polymerases that do NOT proofread the strand being synthesized
- RNA viruses have a very high mutation rate
- A greater percentage of daughter RNA virions are inactive
3
Q
The common cold
A
- usually RNA viruses, specifically rhinoviruses or coronaviruses
- stick to respiratory epithelium and reproduce well below 37C (stick to upper airway)
- chemical mediators like bradykinin produce most of the symptoms
4
Q
Influenza virus
A
Acute infection of upper and lower airways caused by enveloped SS RNA virus
- Influenza A is most common and most severe
- spreads from respiratory droplets and secretions
- enters cell by fusion with cell membrane and causes cell to produce progeny then die
- causes necrosis and desquamation of respiratory epithelium
- rapid onset of fever, chills, myalgia, headaches, weakness, nonproductive cough
5
Q
Parainfluenza virus
A
- paramyxoviridae (RNA) - enveloped, SS, neg sense
- associated with croup (barking cough with stridor on inspiration)
- cause upper and lower respiratory tract infections, especially in young children
- spread from respiratory aerosols and secretions, highly contagious
- infect and kill respiratory epithelium and ilicit inflammatory response
6
Q
Respiratory Syncytial Virus
A
- paramyxoviridae (RNA)
- associated with bronchiolitis in infants
- spread via respiratory aerosols and secretions
- viral surface proteins cause binding and fusion to respiratory epithelium
- produce necrosis and sloughing of epithelium with lymphocytic inflammatory infiltrate
- sometimes can see multinucleated syncytial cells
- symptoms of wheezing, cough, respiratory distress
7
Q
Severe Acute Respiratory Syndrome (SARS)
A
- coronavirus (RNA)
- incubation period of 2-7 days
- causes diffuse alveolar damage and multinucleated syncytial cells without viral inclusions
- fever and headache followed by cough and dyspnea
- lymphopenia and elevated aminotransferase levels present
- can develop ARDS
8
Q
Measles (Rubeola) - RASH
A
- enveloped, single-stranded RNA virus
- upper respiratory symptoms, fever, and rash
- spread via respiratory aerosols and secretions
- viral surface glycoproteins (H and F) mediate attachment and fusion in epithelium, which then spreads to lymph nodes and bloodstream
- rash from action of T lymphocytes on virally infected vascular endothelium
- necrosis of resp epithelium with lymphocytic inflammatory infiltrate
- Warthin-Finkeldey giant cells are fused infected cells that contain up to 100 nuclei - diagnostic
- fever, rhinorrhea, cough, and conjunctivitis –> mucosal or skin lesions
- Koplik spots/mucosal lesions - gray-white dots on a red base that occur in back of cheek
- Skin lesions - begin on face and spread to trunk and extremities - erythematous macropapular rash
- acute encephalitis can occur
9
Q
Rubella - RASH
A
- enveloped, single stranded RNA
- associated with congenital anomolies in utero (deafness, cataracts, glaucoma, heart defects, mental retardation)
- spread via respiratory route
- respiratory epithelium to bloodstream and lymphatics
- rash from immunologic response
- rhinorrhea, conjunctivitis, postauricular lymphadenopathy with rash
10
Q
Mumps
A
- enveloped, single stranded RNA
- characterized by parotid gland swelling and meningoencephalitis
- spread via respiratory route
- enters via respiratory epithelium, disseminates in blood and lymph to salivary glands, CNS, pancreas, and testes
- necrosis of infected cells with lymphocytic inflammatory infiltrate
- fever and malaise to painful swelling of salivary glands
11
Q
Rotavirus - GI
A
- most common cause of severe diarrhea worldwide
- DS RNA virus
- spread via oral-fecal route
- infects enterocytes of upper small intestine, disrupting absorption of sugars, fats, and various ions
- osmotic load causes water rush to lumen, and infected cells are shed - new cells lack full absorptive capability
- duodenum and jejunum - shortening of villi and mild infiltrate of neutrophils and lymphocytes
- vomiting, fever, pain, profuse watery diarrhea
12
Q
Norwalk Virus - GI
A
- nonenveloped RNA calicivirus
- produce gastroenteritis
- changes similar to rotavirus
13
Q
Families of viral hemorrhagic disease and epidemiologic groups
A
Bunyaviridae
Flaviviridae - enveloped, SS RNA
Arenaviridae
Filoviridae
mosquito-borne
tick borne
zoonotic
filoviruses (ROT unknown)
14
Q
Yellow Fever - HEMORRHAGIC
A
- may lead to fulminant hepatic failure
- caused by Aedes mosquito borne flavivirus
- enveloped SS RNA
- virus multiples within tissue and vascular endothelium then through bloodstream
- attracted to liver cells
- can lead to loss of vascular integrity, hemorrhages, and shock
- causes coagulative necrosis of hepatocytes
- Councilman bodies - apoptotic cells
- abrupt onset fever, chills, headache, myalgias, nausea, vomiting, jaundice, loss of clotting factors, bleeding, vomiting blood
15
Q
Ebola virus - HEMORRHAGIC
A
- fruit bat carried RNA filoviridae
- most severely widespread destructive tissue lesions
- virus replicates in endothelial cells, mononuclear phagocytes, hepatocytes and cause necrosis in liver, kidneys, gonads, spleen, lymph
- Liver shows Kupffer cell hyperplasia, Councilman bodies, microsteatosis
- shock
- incubates 2-21 days with headache, weakness and fever followed by diarrhea, nausea, vomiting
