Cls 401 final

viruses

• obligate intracellular parasites

  • depend on host cell for replication

  • viruses CANT

    • make their own energy or substrates

    • make their own protein

    • replicate their genome independently (w/o host cell)

• classified by

  • size

  • genomic material

    • DNA vs RNA (not both)

Herpesviridae

• DNA viruses

• enveloped

DNA vs RNA viruses

• stability

• infection

• location

• interaction

Feature	DNA Viruses	RNA Viruses

Stability

not transient or labile (stable)

Labile and transient

Infection

Many establish persistent infections

prone to mutation

Location of Replication

reside in the nucleus

replicate in the cytoplasm

Interaction

Viral DNA resembles host DNA for transcription and replication and interact w/ host machinery

Must code for own RNA polymerase transcribes DNA sequence into RNA sequence/ carry polymerases

enveloped vs nonenveloped

• structure

• resistance

• survival

• spread

• examples

Feature	Non-enveloped Viruses	Enveloped Viruses

Structure

Naked, rigid capsid

Lipid membrane envelope surrounding capsid

Environmental Resistance

hardier & more resistant to: temperature acid proteases detergents poor sewage treatment drying

labile (sensitive) to acid detergents drying heat

Survival

dry out, retain infectivity survive adverse conditions of the gut hard to kill

Cannot survive GI tract

Spread

spread easily: Hands, fomites, dust, small droplets super infectious

Large droplets, secretions, organ/tissue transplants, blood transfusions

Examples

Norovirus, Poliovirus, Rotavirus, Rhinovirus

Measles, Mumps, Rubella, HIV, Rabies, Coronavirus

basic steps in viral disease (7)

1. acquisition : entry into body

2. infection at primary site : innate reponse activated

3. incubation period : virus undergoing amplication, may spread to secondary site

4. replication in target tissue: characteristic disease signs are revealed

5. host response : immunopathogenesis

6. viral production in tissue that releases virus to other people

7. resolution vs persistant/chronic infection : get better or just die

• latent period: you have infection but not infectious yet

• infectious period: transmit disease to others

• incubation period: dont have symptoms

• symptomatic period: clinical symptoms

stages of disease

4 potential outcomes of viral infection of a cell

1. failed/abortive infection: yay!

2. cell death: cytolytic infection, boo!

3. replication without cell death: persistant infection

4. presence of virus without virus production, but with potential for reactivation: ticking time bomb!

hepatitis types & what do they target/affect?

A,B,C,D,E,G

• all target hepatocytes

• all affect liver

Hepatitis A Virus (HAV) transmission?

• fecal-oral transmission

Hepatitis B Virus (HBV) genetic material?

• DNA

  • only one. the rest of hepatitis is RNA

Hepatitis C Virus (HCV) is known for what?

• chronicity 60-85%

  • highest compared to others

Hepatitis D Virus (HDV) coinfection w/?

• exists as co-infection w/ HBV

  • can replicate only w/ HBV

Hepatitis E Virus (HEV) transmission?

• fecal-oral transmission

Hepatitis G Virus (HGV) chronicity and infection?

• unknown

which hepatitis virus are bloodborne?

HBV

HCV

HDV

which hepatitis are vaccine preventable?

HAV

HBV

hepatits

inflammation of liver

icterus (jaundice)

yellowing of skin or whites of the eyes

cirrhosis

replacement of liver tissue —> fibrosis, scar tissue

liver function tests (LFT)

ALT/AST

• haemolytic : normal

• hepatic: increase

• cholestatic: normal/mild increase

• enzymes going up bc liver cells being destroyed

Hepatitis A Virus

• fecal oral

• no specific treatment, replacement of fluids

• vaccine preventable

VPg

viral (protein genome linked) attached to RNA, acts as a primer to RNA synthesis

Hepatitis B Virus

• bloodborne pathogen

• vaccine preventable: HbsAg - used to make HBV vaccine

  • stands for surface antigen

Hepatitis B Virus Structure

Chronic Hepatitis B

• chronic : antigen never goes away

• persistance of HBsAg for >6months

interpretation of serologic results

Hepatitis C Virus (HCV)

• bloodborne pathogen

• chronic

• no vaccine

• who is at risk:

  • ppl w/ HIV infections

  • ppl who use injection drugs

  • ppl w/ hemodialysis

  • prior transfusions, transplants

  • health care

  • ppl born from 1945-65 ; boomers!

what do you look for in HCV?

RNA

• to detect HCV RNA, you need RT-PCR ( reverse transcriptase polymerase chain rxn)

  • have to first make it into DNA so it can be detected

Hepatitis D Virus (HDV)

• bloodborne pathogen

• occurs in people who are also infected w/ heptatitis B virus

  • co-infection: become infected w/ both hepatitis B and heptatitis D at the SAME time

  • superinfection: get hepatitis D after first being infected with the hepatitis B virus

• No vaccine, however, protection against HBV will protect against future HDV infection

• who is at risk? ppl chronically infected w/ HBV

diagnostic testing for HDV

serologic: anti-HDV Ab

NAT: HDV RNA

Heptatitis E Virus (HEV)

• fecal oral

• rare

• NO vaccine

HIV is what type of virus?

RNA

• requires reverse transcriptase to convert RNA into DNA

HIV infects what cells?

CD4+ cells

CD4+T cells (helper T cells)

proteins associated with HIV

• gag, p24: core proteins

• pol

• env

what is used by HIV strains to enter cells?

CCR5

• a chemokine receptor

• viruses get immune to it

HIV enters what phase?

latent/asymptomatic

what usually kills patients?

opportuinistic organisms and conditions

first marker for Acute Primary HIV?

p24

Acquired Immunodeficiency Syndrome (AIDS)

you either have AIDS condition or CD4 count <200 cells/mm3

PrEP: Pre-Exposure Prophylaxis

medication that prevents HIV infection

Gastrointestinal Viruses

• what are they?

• what do they have in common?

• norovirus (Calicivirus)

• Hepatitis A : fecal bug

• Rotavirus

• Poliovirus (enterovirus)

they are all RNA viruses and have NO envelope

which Gastrointestinal Viruses are vaccine preventable?

• Rotavirus

• Poliovirus

Norovirus

• non-enveloped

• highly infectious

• acute fluid, severe dehydration

• difficult to kill

transmission for Norovirus?

fecal-oral

common outbreak for Norovirus ?

cruise ships

clinical presentation for Norovirus?

• nausea, vomitting

• watery diarrhea

  • poo and puke all at once

Rotavirus

• wheel

• highly infectious

• vaccine preventable

transmission of Rotavirus ?

fecal-oral

who is at risk for Rotavirus?

children 4-36 months; toddlers

a lot of the problems w/ Rotavirus is due to what?

• its a toxin : enterotoxin

  • and killing cells

  • causes secretory diarrhea

Poliovirus (Enterovirus)

• non-enveloped

• super resistant !

• no cure but vaccine preventable

transmission for Poliovirus (Enterovirus)

• fecal-oral

Poliovirus Pathogenesis

• how it gets there

eat it, gets to lymph nodes, goes to blood, then BBB

when it passes BBB, it is an issue

neurologic phase: PARALYSIS

clinical symptoms of Poliovirus in severe cases?

paralytic polio

for Poliovirus, before vaccine this was used to help patient recover and breathe on their own

Iron Lung

inventor of Polio Vaccine?

Jonas Salk

Oral Polio Vaccine is __

Inactivated Polio Vaccine is ___

cVDPV

• alive

  • new strains, vaccines now, but a risk to regain virulence

• dead

• circulating vaccine derive poliovirus

Influenza

• which ones are seasonal epidemic?

• which ones are flu pandemics?

• A, B: seasonal epidemic

• A : the only one that causes flu pandemic

• C: mild, not any epidemics

• D : infect cattle

which respiratory viruses are vaccine preventable?

• measles

• rubella

• mumps

Innate Immune Response

Good and Bad

• too much or too little immune response is a problem

  • want just the right amount

proteins associated with Flu

• HA: hemagglutinin

• NA: neuraminidase

Antigenic Drift vs Shift

• drift: small genetic mutations

  • change NA and HA

• shift: abrubt, major change in Flu A virus

  • new HA and/or NA

Influenza Diagnosis

rapid antigen testing

RT-PCR

Respiratory Syncytial Virus (RSV)

• there are new vaccines for adults: moms, older ppl

• babies get more of the passive immunoglobulin

• what are we worried about? infants and young children, and older ppl (65+)

  • fatal

Human Parainfluenza Virus (HPV)

• respiratory virus

• 4 types: 1,2,3,4

croups is associated with what virus?

HPV: human parainfluenza viruses

• barky cough

  • infection of vocal cords Larynx, windpipe Trachea, bronchial tubes Bronchi

Rhinovirus

• a common cold

• no vaccine

Measles (Rubeola)

• highly contangious

• vaccine preventable

Measles (Rubeola) Clinical Presentation

Symptoms:

• rash

• Koplik Spots

complications:

• Encephalitis leads to deafness bc it can go to your brain

• Death

weird response:

• immune amnesia - makes you forget

Mumps

• highly contagious

• vaccine preventable

Mumps Clinical Presentation

• swollen salivary glands

• swelling

• meningitis: swelling of meninges

Rubella (German Measles)

• vaccine preventable

who are we worried about getting Rubella (German Measles)?

pregnant ladies

• we are trying to prevent Congenital Rubella Syndrome (CRS)

Enterovirus symptoms

Severe Cases

• acute flaccid paralysis

  • enterovirus D68

which ones belong to the Herpesviridae?

• Herpes Simplex (HSV 1,2)

• Varicella zoster virus (VZV)

• Epstein Barr Virus (EBV)

• Cytomegalovirus (CMV)

which Herpesviridae are vaccine preventable?

• Varicella Zoster Virus (VZV)

  • chickenpox

  • shingles aka “zoster”

what does Herpesviridae cause?

latent and lytic

• go away but they are never really gone, they come back and destroy your cells

Herpes Simplex 1 (HSV-1) vs Herpes Simplex 2 (HSV-2)

• Herpes Simplex 1 (HSV-1) : oral

• Herpes Simplex 2 (HSV-2) : genital

Non-Genital Herpes Infection

• Primary Infection

• Oral HSV-1 Infection

Herpes simplex encephalitis (HSE) is the most common cause for what?

Sporadic non-seasonal encephalitis

• attacks the brain

Ocular (eye) Herpes Simplex

• is reccurent : it follows the optic nerve pathway

Genital Herpes

• hides out and comes back

• increase risk of HIV/ STDs

• Neonatal Herpes

when thinking of congenital problems, think of what?

TORCH

Herpes Simplex Virus (HSV) Diagnostics

looks like “owl eye”

Varicella Zoster Virus (VZV)

• chicken pox: primary exposure

• shingles: secondary, reactivation

• vaccine preventable

chickenpox

• itchy, painful

  • complications: pneumonia, encephalitis

• has different stages

  • waiting for Stage 3: crusting

• vaccine preventable

Shingles (Zoster)

• a reactivation

• where it shows up depends on which nerve pathway

• dermatones

what is dermatone?

• nerve pathway from spinal cord then feed into certain area of skin, this is where you see it

  • if it shows up on more than one dermatone, its disseminated, NOT localized

    • localized = contact isolation

    • disseminated = airborne

Epstein-Barr Virus (EBV) associated w/ what?

• Infectious Mononucleosis

• Cancers:

  • B-lymphocytes

  • Epithelial Cells

  • Natural Killer T cells

Infectious Mononucleosis (IM) symptoms

• swollen lymph nodes

• enlarged spleen

Peripheral Blood smear of Infectious Mononucleosis (IM)

• activated, big

• ballerina skirt, scalloped margins

• vacuolated cytoplasm

Cytomegalovirus (CMV)

• its primary then its hiding out

• recurrent CMV: transplant patients

• congenital CMV: most common infectious cause of birth defects in US

  • virus passed to fetus from moms blood through placenta

TORCH

infectious acquired utero or during birth process that are associated w/ miscarriage and/or congenital abnormalities

• T = toxoplasmosis

• O = other

  • Syphilis

  • Parvovirus

  • VZV

  • Listeria

• R = Rubella

• C = CMV

• H = HSV

Most Common Cause of Disseminated Intravascular Coagulation (DIC)?

sepsis

serotypes of Dengue

• DENV-1

• DENV-2

• DENV-3

• DENV-4

you can be infected up to 4 times in your life

• AB to one serotype increases likelihood you will have more severe infection the next time

for Zika Virus, what are we worried about?

Congenital Zika Syndrome

• microcephaly

Where is West Nile Virus (WNV) transmitted?

• mosquito

• birds

what disease is involved w/ West Nile Virus (WNV)?

CNS involvement