401 EXAM 2

viruses

HSV, VZV, EBV, CMV; ENV+

Herpesviridae

they are not transient nor labile

many establish persistent infections

they often reside in the cell nucleus

genetic material resembles host’s material for transcription and replication and interacts with host machinery

DNA viruses

they are labile and transient

they are prone to mutation

most replicate in the cytoplasm

they must code for their own polymerase

RNA viruses

they are hardier and more resistant to the environment

ex: norovirus, poliovirus, rotavirus, rhinovirus

non-enveloped viruses

they are sensitive to the environment

they cannot survive the GI tract

ex: measles, mumps, rubella, HIV, rabies, coronavirus

enveloped viruses

The stages of a disease (5) and which stage exhibits the most severe symptoms?

hint: i, p, i, d, c

enveloped RNA virus that infects CD4+ cells, T helper cells, and immune system

Human Immunodeficiency Virus

(can progress to AIDS)

this type of HIV is the predominant one worldwide

HIV-1

HIV-2 is primarily in west africa, europe, and india

the proteins on an HIV cell that are tested to detect HIV

envelope proteins: gp41, gp120

inside: p17, p24 (predominant capsid protein)

when a person with HIV gets another type, or strain, of the virus. if the new strain is resistant to medicine/therapy that the person is already taking, it may cause quicker illness

superinfection

patient doesn’t adhere to the medication directions

(who the hell has time for nausea??)

inadequate adherence

describe: latent/asymptomatic HIV infection

immune cells are infected with HIV virus but not actively producing new HIV infected cells

T/F: you can test for HIV right away

Fasle: anti-p24 antibodies appear 1-2months; correlated with the decline in p24

if tested too soon, could result in false negative

What is the criteria of AIDS?

AIDS-defining condition

or

CD4 count less than 200 cells/mm3

label HSV structure from top to bottom

T/F: incubation period can be longer than the latent period, meaning you can start being infectious while asymptomatic

true!

HIV enters a host cell and has to undergo _______ before integration and replication.

reverse transcription to synthesize cDNA

________ testing uses viral components p24, p31, gp41, gp120/160 to detect HIV

Confirmatory Testing

medication that prevents HIV infection for HIV-negative high risk individuals

PrEP: pre exposure prophylaxis

hepatitis virus(es) with fecal-oral transmission

HAV, HEV

hepatitis virus(es) with DNA genetic material

hint: bloodborne pathogen

HBV

hepatitis virus(es) with 60 – 85% chronicity

hint: bloodborne pathogen

HCV

hepatitis virus(es) that exist(s) as a co-infection

hint: bloodborne pathogen

HDV requires HBV to replicate

another word for icterus is ________

jaundice

acute vs. chronic hepatitis

acute: symptoms present for less than 6 months

chronic: HBsAg present for more than 6 months

replacement of liver tissue with scar tissue (fibrosis)

liver cirrhosis

severe impairment of hepatic functions or severe necrosis of hepatocytes in the absence of pre-existing liver disease

fulminant hepatitis

this marker is used to make the HBV vaccine

HBsAg (surface antigen)

beyond the surface, ______ antigen is found within the Hepatitis B virus structure

core antigen

HBsAg: (-)

Anti-HBs: (-)

Anti-HBc: (-)

what does this mean?

patient is susceptible to HBV

HBsAg: (-)

Anti-HBs: (+)

Anti-HBc: (-)

what does this mean?

patient is vaccinated successfully

HBsAg: (-)

Anti-HBs: (+)

Anti-HBc: (+)

what does this mean?

patient had a past infection but cleared it successfully

HBsAg: (+)

Anti-HBs: (-)

Anti-HBc: (+, IgM)

what does this mean?

patient has an acute HBV infection

HBsAg: (+)

Anti-HBs: (-)

Anti-HBc: (+, IgG)

what does this mean?

patient has a chronic HBV infection

Why can’t HDV survive without HBV?

HDV shares the envelope glycoproteins of HBV. HDV uses HBsAg to enter the cell, so HDV can’t enter host cells alone

rotavirus

norovirus

enterovirus/poliovirus, HAV

are all examples of???

non-enveloped RNA viruses

non-enveloped RNA virus

causes acute infectious gastroenteritis

difficult to disinfect (HIGHLY INFECTIOUS)

known for spreading on cruise ships

norovirus (norwalk virus)

non-enveloped RNA virus

highly infectious

common symptoms include severe watery diarrhea, vomiting, fever, dehydration, crying with few or no tears, decreased urination

population at risk: little babies

rotavirus

“wheel” in latin

nonstructural protein NSP4 that induces secretory diarrhea without any structural organ damage (rotavirus)

enterotoxin

non-enveloped RNA enterovirus

can infect CD155+ cells (intestinal epithelial cells)

fecal-oral transmission

known for causing paralysis

poliovirus

why is poliovirus so deadly?

polio replicates in the oropharyngeal and intestinal mucosa, eventually spreading to the tonsils and lymphatic tissue in the small intestine

once the virus enters the bloodstream in the viremic phase, it can spread to the spinal cord and cross the blood-brain barrier, destroying nerves and causing paralysis

only this type of influenza can cause pandemics

Influenza type A

how is influenza A virus subtyped?

HA: hemagglutinin

NA: neuraminidase

(ex: H1N1)

enveloped virus

population at risk: babies and elderly

most common cause of bronchiolitis and pneumonia in infants and children

acute respiratory tract illness

these tests in the lab are STAT

respiratory syncytial virus (RSV)

enveloped virus

causes barking cough (croup)

upper and lower respiratory illness

human parainfluenza virus (HPIV)

enterovirus that causes the common cold

no vaccine

rhinovirus

enveloped RNA virus

aka “rubeola”

airborne transmission

Koplik spots inside mouth

rash breaks out on face first, then spreads down

measles

enveloped RNA virus

swollen salivary glands

more common during childhood

Mumps

enveloped RNA virus

may cause a rash that begins on face and spreads

causes severe birth defects when exposed to a developing baby in utero, esp in first trimester

hint: vaccine preventable (MMR)

rubella (german measles)

non-enveloped DNA virus

symptoms depend on the serotype but it’s most associated with respiratory complications in young children

vaccine for this virus is for military personnel only

many serotypes (>60)

adenovirus

coxsackievirus, acute flaccid paralysis (enterovirus D68) and viral conjunctivitis are examples of _________ enteroviruses

non-polio enteroviruses

Herpesviridae viruses can cause _______ and ________ infections, meaning they can reactivate, never going away

latent: asymptomatically persist in host

lytic: destroys cell upon release of new virions

this type of Herpes virus hides in nuclei of trigeminal ganglia and reactivates as oral infections

hint: usually oral/cold sores

HSV-1

this type of herpes hides in the sacral ganglia

hint: STD/gential

HSV-2

most common etiology for sporadic non-seasonal encephalitis across the world

high morbidity and mortality

herpes simplex encephalitis (HSE)

reactivated HSV-1 infection, usually pediatric

ocular herpes simplex

this virus causes chicken pox (primary) and shingles (reactivated)

latency in the dorsal root ganglia

viral cell cultures show rounded cells, sandpaper-like appearance

varicella zoster virus

an area of skin in which sensory nerves derive from a single spinal nerve root

shingles

dermatome

(if 2 dermatome, then the shingles is not localized)

latency in B lymphocytes, epithelial cells, and natural killer/T cells (higher likelihood of cancer in these cells)

body fluid transmission

associated with infectious mononucleosis (IM)

epstein barr virus (EBV)

“kissing bug”, “mono”

kissing disease caused by EBV

symptoms include enlarged spleen

lymphocytes have scalloped margins, indentations by surrounding RBCs, vacuolated cytoplasm

“ballerina skirt”

infectious mononucleosis

this virus has latency in macrophages

especially dangerous in transplant patients (not a reactivation, it’s primary!)

most common infectious cause of birth defects in US

more common w/ women’s 2nd pregnancies; older child’s illness infects mom and fetus

cytomegalovirus (CMV)

hint: turkel’s mystery rash

TO(SPVL)RCH infections that are associated with miscarriage and/or congenital abnormalities

Toxoplasmosis

Other agents: syphilis, parvovirus, VZV, listeria

Rubella

CMV

Herpes

transmission: mosquito to human

common in puerto rico

2nd infection of different serotype hurts worse; host antibodies welcome new strain (open door)

causes endothelial cell dysfunction and coagulation disorder

Dengue

generally milder disease than dengue

biggest issue is infection during pregnancy (causes microcephaly, brain defects)

transmission: mosquito to human

zika virus

present in the US, even in CA

transmission: mosquito

primary reservoir: birds (crows are very sensitive to this)

able to infect neurons and cause encephalitis, flaccid paralysis, meningitis

west nile virus

transmission: mosquito

reservoir: non-human primates

virus replicates in the liver, leading to hepatocyte apoptosis and lytic necrosis

severe illness presents with high fever, yellow skin, bleeding, shock, organ failure

yellow fever

UCLA and Cedars are treatment facilities for this virus

reservoir: bats

zoonotic disease

vascular leakage, hypotension, disseminated intravascular coagulation, and endothelial cell death lead to hemorrhagic fever

ebola virus

explain the ebola virus ecology and transmission

hint: animal to animal, spillover event, human to human, survivor

what are the 3 laboratories in the lab response network for diseases like ebola?

national labs

reference labs

sentinel labs

reservoir: bats

rare virus

results in hemorrhagic fever

marburg virus

reservoir: rat

results in hemorrhagic fever

most common complication: deafness

lassa fever

transmission: from deer mouse & white-footed deer mouse (white fur on bellies, large eyes)

new world virus type: Sin Nombre virus (pulmonary failure)

old world virus type: fever with renal failure

hantavirus

virus is attracted to sebaceous glands

terrorized the world for thousands of years; first disease to be eradicated

virus enters blood during primary viremia, then pustules and scabs form upon secondary viremia

pocks progress at the same stage

variolator first used to inoculate an uninfected person with dried scabs for vaccination

smallpox (variola virus)

this virus attacks the central nervous system and causes fatal encephalitis

transmission: infected animal bite

vaccination of post-exposure prophylaxis upon infection must occur QUICKLY within zone of neutralization

rabies

explain the pathogenesis of rabies

virus enters/replicates in muscle; travels through neuromuscular junctions into peripheral nerves; travels to brain via spinal cord and ganglia; brain infection leads to inflammation (encephalitis); virus enters salivary glands & other organs of host

zoonotic disease

associated with direct contact with infected camels

MERS-COV

specimen collection and transport uses a swab and either viral transport media or universal transport media. the tube contains what 3 things?

balanced salt solution

human cells

antibiotics

why might a fluorescent antibody stain be used?

can perform directly on specimen

organism is difficult to find/isolate/identify/culture

can identify multiple organisms at once in one specimen using different fluorescent markers

high sensitivity and localization

ex: search for parasites in stool sample

the main reagent in fluorescent antibody staining

fluorescently-labeled monoclonal antibodies

direct vs indirect antibody staining

direct: antibodies attach to target antigen in a single step

indirect: unlabeled antibodies attach to target antigen first, then fluorescently-labeled antibody attach to unlabeled antibody

reagents for enzyme immunoassays

monoclonal antibodies, enzyme, substrate

when are rapid enzyme immunoassays used? how do they work?

used for non-culturable viruses like RSV where we want a rapid diagnosis (babies can’t breathe in ER ☹)

substrate + enzyme interaction create color change when enzyme is attached to antibody that matches a target antigen

as prevalence decreases, the more likely you will have ______ _______.

false positives. sensitivity varies and specificity improves as prevalence of infection in community increases

the control line on enzyme immunoassays is looking for what?

reagent from the test (not sample); so if control line is dysfunctional, test is invalid

we are looking for a specific target antibody in these samples in the well plate. an antigen is added to the wells first, then all the patient samples with unknown antibodies. Then a secondary antibody linked to an enzyme is added. then a substrate (chromogen) is added. if target antibodies are present and match with antigen, then the enzyme and substrate will produce a color change to quantitatively or qualitatively detect the target. what is this method called?

enzyme linked immunosorbent assay (ELISA)

T/F: molecular amplification (PCR) is a test of diagnosis, not cure

true. does not differentiate between live/dead organism

how do we amplify genetic material from an RNA virus?

reverse-transcriptase PCR. there is an added step of reverse transcription of RNA to cDNA to allow for amplification

method where the amplified product is measured as the reaction progresses. fluorescence is measured after each cycle

qPCR, called “real time” PCR

describe the TaqMan probe

probe consists of a reporter and a quencher. as long as the quencher is close enough to the reporter, reporter cannot fluoresce. When DNA polymerase begins to build during extension phase, it cleaves the probe, freeing the reporter from the quencher! = measurable fluorescence. if PCR or binding of probe to DNA is unsuccessful, no fluorescence.

When do qPCR measurements occur?

baseline

exponential

linear

plateau

during the exponential signal phase

what is the threshold line?

what do lower and higher CT values mean?

threshold line is the level of detection or the point at which a reaction reaches fluorescent intensity above background noise

higher: lower concentration/negative result or gross error

lower: higher concentration of virus

how would you know what a specific CT correlates to, in terms of viral concentration in the specimen AND what the threshold should be?

standard calibration curve

in real-time PCR, r = -1

how do you create a standard calibration curve for qPCR?

use a series of known concentrations of viral specimens (standards) to determine the CT of each known standard. then plot CT (y) vs concentration (x)

T/F: if a sample falls outside of the standard curve, quantitation is not reliable

true

VERY expensive real-time multiplexed PCR test designed to simultaneously identify nucleic acids from different viruses, bacteria, and parasites for GI, respiratory, etc

syndromic panels

the gold standard to isolate live viruses and show active infection

performed to show CPE: cytopathic effect (structural changes in host cells caused by viral invasion)

expensive

extensie training

takes a long time

viral culture