6 Virus

q123456's version from 2016-05-30 18:05


Question Answer
Viral recombinationExchange of genes between 2 chromosomes
Viral reassortmentviruses with segmented genomes exchange segments
Viral complementationWhen 1 of 2 viruses that infect the cell has a mutation that results in a nonfunctional protein. Nonmutated virus “complements” the mutated one by making a functional protein that serves both viruses
Viral phenotypic mixingOccurs with simultaneous infection of a cell with 2 viruses. Virus A genome can be coated with surface protein of virus B - type B protein coat determines the infectivity of the phenotypically mixed virus. The progeny from this infection have a type A coat form the type A genetic material
Live attenuated viral vaccines----------------------------------------------
live vaccines induce humoral(antibody) and Cell-mediated immunity
killed vaccines only activate humoral immunity.
MMR: measles, mumps, rubella - only live attenuated vaccine that can be given to HIV-positive patients

polio (sabin)
yellow fever(flav)
intranasal influenza
smallpox (pox)
chickenpox (vzv)
hemagglutininparamyxoviridae family
Influ v: H5N1
Hemagglutinin (HA)
1) binds to host cell plasma membrane glycoprotein receptor
2) influenza vaccine: circulating antibody against the hemagglutinin of virus. *Hemagglutinin binds to cells with sialic acid on the membranes
Recombinant viral vaccinesHBV, HPV (6,11,16,18)
Fetal infection with rubella Deafness, PDA
How long does over 80% of women attempting to conceive will be pregnant?One year
Generating several functional virus proteins from a single polypeptideEchovirus
naked RNA induce viral protein synthesis and viral genome replication ss+RNA
How to inactivate enveloped virusesether
EnterovirusesMost common viral meningitis in children
difficulty walking, fever, headache, eye pain
parvoErythema infectiosum
ToxoplasmosisHydrocephalus (big head circumference, intracranial calcifications and chorioretinitis>>>Congenital toxoplasmosis


Question Answer
Anti-IgG against hepatitis C envelop do not confer effective immunity against the infection?Envelope proteins vary their antigenic structure
An unenveloped RNA virus causes hepatitis in pregnant womenHepatitis E
The delata agent is able to cause hepatitis with direct HBV assistance coating of viral particles
The delata agent can infect hepatocytes and multiplyHBsAg coat HDAg of hepatitis
an RNA virus covered by HBV surface antigens
What increases the risk of vertical transmission of hepatitis B from pregnant females to the unborn child?HBeAg
Antiretroviral chemotherapy in HIV patientpol gene mutations

DNA viruses

Question Answer
Naked viral genome infectivitydsDNA(except POX and HBV)
+ strand ssRNA viruses
Virus ploidyhaploid except retroviruses (2 identical ssRNA molecules)
RNA viral replicationin the cytoplasm (except influenze virus and retroviruses)
Naked virusesRNA viruses: "his real california pico" Calcivirus, HEV, Picornavirus, Reovirus,
DNA viruses: Parvovirus, Adenovirus, Papilloma and Polyoma
envelope from nuclear membraneherpesviruses
DNA enveloped virusesHerpesvirus (HSV 1, 2, VZV, CMV, EBV) HBV, POX (smallpox)
RNA enveloped viruse1) all SS-
2) SS+
DNA virus characteristics1. Are double stranded (except parvo)
2. Are linear (except papilloma and polyoma and hepadna)
3. Are icosahedral (except pox)
4. Replicate in the nucleus (except pox) KA35-2 * replication outside of the nuleus: POX, RNA except influenze and HIV
HSV-1trigeminal ganglia
Tzanck test (multinucleated giant cells)
intranuclear Cowdry A inclusions
Kluver bucy syndrome
HSV-1 encephalitis
inappropriate sexual activity
oral fixation

A 28 year old man with HIV infection comes to the physician because of pain on swallowing for 1 week. After a trial with antacids without relief, the patient undergoes endoscopy, which shows punched out ulcers in the lower segment of the esophagus. biopsies from these areas show chronic inflammation and epithelial cells with glassy intranuclear inclusion. ( it is not candida. read the whole question not the first sentence)

HSV-2Herpes genitalis, neonatal herpes
VZV (HHV-3)Chickenpox, zoster shingles, encephalitis, pneumonia;
dorsal root or trigeminal ganglia
young VZV+ patients need test HIV
KA36-47,KA37-27 --> Reye
EBV (HHV-4)saliva
Infects B cells
Mononucleosis:Fever, hepatosplenomegaly, pharyngitis, lymphadenopathy
Abnormal circulating cytotoxic T cells (atypical lymphocytes, CD8+)
Hodgkins, endemic Burkitt’s, nasopharyngeal carcinoma.
Positive monospot test, heterophil antibodies detected by agglutination of sheep RBCs
CMV (HHV-5)Monospot (-) mononucleosis, retinitis
owl’s eye appearance
latent in mononuclear cells
cytomegalovirus:hyperemia and ulcerations of esophageal mucossa
HHV-6Roseola (exanthem subitum) - high fevers for several days that can cause seizures followed by diffuse macular rash
HHV-8Kaposi’s sarcoma
the tumor has an appearance very similar to the angiosarcoma
Vaccine available with surface Ag
not a retrovirus but has reverse transcriptase;
Adenovirusacute hemorrhagic cystitis
Conjunctivitis (watery pink eye) KA23-15
Not enveloped
B19 Virus
>>>aplastic crises in sickle cell disease
>>> “slapped cheeks” rash in kids - erythema infectiosum (fifth disease),
>>>RBC destruction in fetus leads to hydrops fetalis and death;
>>>pure RBC aplasia and RA like symptoms in adults
PapillomavirusHPV -warts (1,2,6,11), CIN, cervical cancer(16,18)
cervical cancer is associated with p53 and RB
koilocytic cells KA32-8
PolyomavirusJC (junky cerebrum)-progressive multifocal leukoencephalopathy (PML) in HIV
BK virus (Bad Kidney) in transplant patients
Poxviruslargest dsDNA
Replication in cytoplasm
Smallpox (eradicated)
Vaccinia (cowpox)

RNA Viruses

Question Answer
Reoviruses1. No envelope
2. DS
3. 10-12 segments
4. Double Icosahedral
5. Coltivirus Rotavirus - #1 cause of fatal diarrhea in children
PicornavirusesPolio, Echo, Rhino (common cold), Coxsackie, HAV
CalcivirusesNorwalk virus -viral gastroenteritis
FlavivirusesHCV, Yellow fever, Dengue, St. Louis encephalitis, West nile virus
TogavirusesRubella (german measles), Eastern equine encephalitis, Western equine encephalitis
RetrovirusesHave reverse transcriptase
CD4 positive cells declines>>> antibody other than IgM will declines
CD4 cells low
anti-p24 low
viral load increases
anti-gp41 and anti-gp120 IgM remain stable or increase slightly
HIV patients sudden high fever, severe dyspnea and malaise-pneumocystic jiroveci (silver stain or direct fluorescent antibody test)

AIDS patient develops a fever, headache and stiff neck. CSF: Lymphocytes, glucose of 35 mg/dl, protein of 75 mg/dl>>>cryptococcus neoformans>>>latex particle agglutination
HTLV (T-cell leukemia)
CoronavirusesCommon cold and SARS
OrthomyxovirusesInfluenza virus
ParamyxovirusesParainfluinza (croup)
RSV (bronchiolitis in babies- tx with Ribavirin)

paramyinfluenza: croup: barking cough
Haemophilus influenza: epiglottitis: inspiratory stridor
mumps:parotitis/orchitis (neutrophils) -plasma cell inflammation-syphilis
painful pharyngeal muscular spasms
eosinophilic cytoplasmic inclusions (negri bodies) in the hippocampal neurons
FilovirusesEbola/Marburg hemorrhagic fever - often fatal
ArenavirusesLCMV - lymphocytic choriomeningitis virus
BunyavirusesCalifornia encephalitis, Sandfly/Rift valley fevers, Crimean-Congo hemorrhagic fever, Hantavirus - hemorrhagic fever, pneumonia;
Coxsackie virusa picornovirus
aseptic meningitis
herpangina (mouth blisters, fever)


Question Answer
Ribavirininhibits IMP dehydrogenase
used for RSV, HCV
SE: Hemolytic anemia, severe teratogen
IFNa+Ribavirin >>>hepatitis C
AcyclovirMonophosphorylated by HSV/VZV thymidine kinase.
Guanosine analog.
inhibits viral DNA polymerase by chain termination
Clincal use: HSV, VZV and EBV
resistant: lack of viral kinase
foscarnetViral DNA polymerase inhibitor
Does not require activation by viral kinase
Clincal use: CMV retinitis in IC patients when Ganciclovir fails.
Toxicity: Nephrotoxicity
resistant: mutanted DNA polymerase
Ganciclovir5' monophosphate formed by a CMV viral kinase
Guanosine analog,
inhibits viral DNA polymerase
Clinical use: CMV
Toxicity: Leukopenia, neutropenia, thrombocytopenia, renal toxicity.
resistant: lack of viral kinase

Anti-influenza virus

Question Answer
(inhibit uncoating)
prevent the release of infectious viral nucleic acid into the host cell by interfering with the function of the transmembrane domain of the viral M2 protein.
Clinical use: prophylaxis and treatment for Influenza A only; Parkinson's disease
Toxicity: Ataxia, dizziness, slurred speech
resistant: mutated M2 protein
Rimatidine:Derivative with fewer CNS side effects. Does not cross BBB
(inhibit exit)
Inhibit influenza neuraminidase, decreasing the release of progeny virus
Clinical use: both Influenza A and B, mainly prophylaxis
(inhibit penetration)
fusion inhibitor
binds viral gp41 subunit, inhibit conformational change required for fusion with CD4 cells, blocking entry and replication
used for patients with persistent viral replication despite antiretroviral therapy


Question Answer
protease inhibitors for HIV"navir“
RT: RNA dependent DNA polymerase
completely inhibit nucleotide binding to RT and terminate the DNA chain.
must be phosphorylated by thymidine kinase to be active
NNRTIs "VIR"nevirapine
binds to RT at site different form NRTIs
Do not require phosphorylation to be active or compete with nucleotides
synergistic if use in combination with NRTIs and/or PIs
antiretroviral drugs-indinavirlipodystrophy, hyperglycemia and inhibition of p 450
zidovudine's SEAnemia
anti HIVenfuvirtide (gp 41 not gp120, fusion inhibitors)

navir(protease inhibitors)

efavirenz, tenofovir, vudine(RT inhibitors)

raltegravir (integrase inhibitors): double stranded viral DNA enters the host cells nucleus and insert into the host choromosomes by integrase.

maraviroc (CCR5 receptor inhibitors)