Virology Flashcards
phenotypic mixing
Simultaneous infection of a cell with 2 viruses
Genome of virion A can be partially or completely coated forming a pseudovirion with the surface proteins of virus B
Type B protein coat determines the tropism (infectivity) of the hybrid virus
Progeny have a type A coat that is encoded by its type a A genetic material
All RNA viruses have ssRNA genomes except
Reoviridae (dsRNA)
+ssRNA
Retrovirus Togavirus Flavivirus Coronavirus Hepevirus Calicivirus Picornavirus
“I went to a retro Toga party where I drank flavored Corona and ate hippie Cali pickles”
(-) vs (+) strand
mostly : (+) strand purified nucleic acids are infectious
but (-) strand are not and require polymerase contained in the complete virion. Virion brings its own RNA dependent RNA polymerase
Nonenveloped/naked viruses
“give PAPP smears and CPR to a naked hippie”
Papillomavirus Adenovirus Parvovirus Polyomavirus Calicivirus Picornavirus Reovirus Hepevirus
DNA viruses
they are HHAPPPPy viruses
Hepadna –> HBV, not retrovirus, has reverse transcriptase
Herpes
Adeno –> febrile pharyngitis, pink eye, etc
Pox –> molluscum contagiosum
Parvo –> B19 virus causing a slapped cheek rash in children. RBC destruction in fetus –> hydrops fetalis. Aplastic crisis and RA sx
Papilloma –> warts are 6,11. Cervical cancer are 16 and 18
Polyoma –> JC virus causes progressive multifocal leukoencephalopathy (PML) in HIV. BK virus transplant patients commonly targets kidneys
All DNA viruses are double stranded except
Parvo
All DNA viruses replicate in the nucleus except
Poxvirus
“Pox is out of the box (nucleus)
HSV1
Keratoconjunctivitis and herpes labialis
Herpetic whitlow on finger
Temporal lobe encephalitis (most common cause of sporadic encephalitis)
Trigeminal ganglia
HSV2
Herpes genitalis and neonatal herpes
Sacral ganglia
Viral meningitis more common compared to HSV1
HSV3
Spread via resp secretions
Varicella zoster
Most common cause of shingles is post herpetic neuralgia
Latent in dorsal root or trigeminal ganglia. If CN V1 is involved then it can cause herpes zoster ophthalmicus
EBV or HHV-4
Epstein Barr Virus (HHV-4) - infects B cells through CD21. Atypical lymphocytes on peripheral blood smear (due o cytotoxic T cells)
“kissing disease” or mononucleosis - fever, hepatosplenomegaly, pharyngitis, lymphadenopathy (esp posterior lymph nodes)
AVOID contact sports due to risk of splenic rupture
Associated with Burkitt lymphoma, nasopharyngeal carcinoma, lymphoproliferative diseases in transplant pt
+monospot test - heterophile antibodies detected by agglutination of sheep or horse RBCs
Amoxicillin causes characterisitc maculopapular rash
Cytomegalovirus (HHV-5)
(-) monospot test in immunocompetent pt
pneumonia in transplant pts
AIDS retinitis “sightomegalovirus”: hemorrhage, cottom-wool exudates, vision loss
“owl eye” intranuclear inclusions
HHV 6 and 7
spread via saliva. Fever first, rosy rash later
Roseola infantum (exanthem subitum): high fever for several days that can cause seizures followed by a diffuse macular rash.
HHV 8
Sexual contact
Kaposi sarcoma (neoplasm of endothelial cells) in HIV/AIDS p and transplant pt
dark/violaceous plaques or nodules representing vascular proliferation
Tzanck test
a smear of an opened skin vesicle to detect multinucleated giant cells commonly seen in HSV 1, HSV2, VZV . Can also see intranuclear eosinophilic cowdry A inclusions
“Tzanck heavens I do not have herpes”
Receptors used by viruses
CMV EBV HIV Parvovirus B19 Rabies Rhinovirus
CMV - integrins (heparan sulfate) EBV- CD21 HIV - CD4,CXCR4, CCR5 Parvovirus B19 - P antigens on RBCs Rabies- Nicotinic AChR Rhinovirus- ICAM-1
(-) RNA
Always Bring Polymerase Or Fail Replication
Arenavirus Bunyavirus Paramyxovirus Orthomyxovirus Filovirus Rhabdovirus
Segmented virus
BOAR
Bunyavirus
Orthomyxovirus (influenza virus)
Arenavirus
Reovirus
Picornavirus
Poliovirus, Echovirus, Rhinovirus, Coxsackievirus, HAV
1 large polypeptide that is cleaved by proteases into function viral proteins
aseptic viral meningitis and enteroviruses (except Rhino and HAV)
Rhinovirus
A Picornavirus
Common cold
Acid labile - destroyed in stomach acid –> cant infect GI
Pt presents with high fever, black vomit, and jaundice
Yellow fever virus (a flavivirus)
Aedes mosquitoes
councilman bodies (eosinophilic apoptotic globules) on liver biopsy
Rotavirus
dsRNA virus (reovirus)
Most important global cause of infantile gastroenteritis
villous destruction with atrophy leads to decreased absorption of Na+ and loss of K+
vaccinate all children except SCID pt
Influenzavirus
Orthomyxoviruses
eight segment genome
Contains hemagglutinin (binds sialic acid and promotes viral entry) and neuraminidase (promotes progeny virion release) antigens
pt at risk for super infection via S aureus, S pneumo, and H influenzae
Genetic/antigenic shift causes pandemics
Genetic/antigenic drift causes epidemics
Rubella virus
Togavirus
Fever, postauricular and other lymphadenopathy, arthralgias, and fine maculopapular rash that starts on face and spreads centrifugally to involve trunk and extremities
Serious congenital disease - “blueberry” muffin appearance due to dermal extramedullary hematopoiesis
Paramyxoviruses
Cause disease in children
Surface (F) protein which causes respiratory epithelial cells to fuse and form multinucleated cells
give Palivizumab (monoclonal Ab against F protein) as prophylaxis to premature infants
Croup or acute laryngotracheobronchitis
Parainfluenza virus (paramyxovirus)
Hemagglutinin which binds sialic acid and promotes viral entry and neuraminidase (promotes progeny virion release) antigens
“seal like” barking cough and inspiratory stridor
Steeple sign on xray - narrowing of uppe trachea and subglottis
Severe croup –> pulsus paradoxus secondary to upper airway obstruction
Measles virus
Rubeola (paramyxovirus)
prodromal fever with cough, coryza, and conjunctivitis
Koplik spots - bright red spots with blue-white center on buccal mucosa. Followed by a maculopapular rash that starts at the head/neck and spreads downward
lymphadenitis with warthin-finkeldey giant cells (fused lymphocytes) in background of paracortical hyperplasia
Mumps virus
Parotitis (inflammation of parotid glands)
Orchitis (inflammation of testes)
Aseptic meningitis
Pancreatitis
Rabies Virus
bullet shaped virus
Negri bodies (cytoplasmic inclusions) commonly in purkinje cells of cerebellum and hippocampal neurons
Travels to the CNS by migrating in retrograde fashion (via dynein motors) up nerve axons after binding to ACh receptors
Ebola virus
Filovirus
targets endothelial cells, phagocytes, hepatocytes
diarrhea, vomiting, high fever, myalgia, progression to DIC, difuse hemorrhage, shock
dx with RT-PCR 48 hrs after sx onset
Zika virus
Flavivirus
Aedes mosquito
conjuntivitis, low grade pyrexia, and itchy rash
congenital microcephaly
HAV liver biopsy
Hepatocyte swelling
Monocyte infiltration
Councilman bodies
HBV liver biopsy
Granular eosinophilic “ground glass” appearance
Cytotoxic T cells mediate damage
HCV liver biopsy
Lymphoid aggregates with focal areas of macrovesicular steatosis
HDV
Super infection (HDV after HBV) = short
coinfection (HDV with HBV) = long
Defective virus because it depends on HBV HBsAg coat for entry into hepatocytes
HEV
Fecale-oral, especially water borne
fulminant hepatitis in Expectant (pregnant) women
High mortality in pregnant women
Liver biopsy shows patchy necrosis
Anti-HAV (IgM)
Anti-HAV (IgG)
acute hep A
prior HAV infection/vacccination –> prevents reinfection
HBsAg
Antigen of HBV
Hep B infection
Anti HBs
antibody to HBsAg
immunity due to past Hep B or vaccination
HBcAg
Antigen associaed with core of HBV
Anti-HBc
Antibody to HBcAg
IgM = acute/recent IgG= prior or chronic infection
HBeAg
secreted by infected hepatocyte into circulation
active viral replication
Anti HBe
antibody to HBeAg
HIV
Diploid genome ( 2 molecules of RNA)
env (gp120 and gp41) - gp120 attaches to host CD4+ and gp41 is for fusion and entry
gag (p24 and p17) - p24 is capsid and p17 is a matrix protein
pol - reverse transcriptase, aspartate protease, integrase
Virus binds CD4 and either CCR5 on macrophages in early infection or CXCR4 on T cells in late infection
homozygous CCR5 mutation = immunity
heterozygous CCR5 mutation = slower coarse
HIV dx
AIDS dx when < or equal to 200 CD4 cells
first do a HIV1/2 Ag/Ab immunoassay which detecs viral p24 capsid protein and IgG abs to HIV 1/2
Confirm with HIV 1/2 ab differentiation immunoassay which tells you if its HIV 1/2
Inconclusive? nuclec acid amplification test (NAAT). If negaive then it was a false positive inititally
Prions (not a virus)
conversion of a normal alpha prion protein (PrP^c) to a beta pleated form (PRP^sc) which is transmissible via CNS related tissue or food contaminated by BSE infected animal products
PRP^sc resists protease degradation and facilitates teh conversion of still more PrP^c to PrP^sc
ultimately results in spongiform encephalopathy and dementia, ataxia, and death
Creutzfeldt-Jakob disease
prion disease
rapidly progressive dementia
sporadic
Bovine spongiform encephalopathy
mad cow disease
Kuru
acquired prion disease
tribal populations
human cannibalism
