Viral Agents Flashcards
structure of a virus?
protein capsid surrounds DNA or RNA, never both. no enzymes.
Positive vs Negative strand RNA virus
positive strand is like mRNA and can be translated immediately.
Negative stand must be transcribed into a positive stand to be translated into protein. this is done by an RNA dependent RNA polymerase.
how do retroviruses replicate?
they use a reverse transcriptase to turn their RNA into DNA and add it to the host genome.
double stranded RNA virus
retrovirdae, including rotavirus is the only virus with double stranded RNA genome
Negative vs Positive strand in DNA viruses?
the negative strand is the strand that is transcribed inot mRNA and the pos strand is ignored.
explain how a capsid is made
a capsid is a made from capsomer building blocks. glue them together into a triangle, then add 20 triangles together and a capsid is formed!
naked for enveloped virus
enveloped has a plasma membrane surrounding it.
naked viruses don’t.
Name the DNA viruses
HHAPPPy: Herpes Hepandna Adeno Papova Parvo Pox
where do DNA viruses replicate vs RNA viruses?
DNA - nucleus
RNA - cytoplasm
Single stranded DNA Virus
Parvoviridae
very complex virus with double stranded DNA , coding for hundreds of proteins. it is surrounded by box proteins and replicates in the cytoplasm, not nucleus.
Poxviridae
DNA viruses with envelopes?
Herpes, Hepadna, Pox
three naked DNA viruses
Papova, Adeno, Parvo
four exceptions for RNA viruses
- reoviridae is double standed RNA
- three are enveloped : Picoma, Calici, revirdae
- five have icosahedral symmetry: Reo, Ricoma, Togo, Tlavi, Calici
- (Rhabdo has helical symmetry and its shaped like a bullet.
enzymes to replicate RNA
Replication:
POSITIVE RNA = have the RNA dependent RNA polymerase
NEGATIVE RNA = VIRON RNA POLYMERASE
steps in DNA transcription and translation of viral DNA
early vs late
early transcription = translation of proteins for DNA and replication
Late Transcription = translation of structural proteins and assembly.
possible host cell outcomes when Viral DNA replicates
Host cell outcomes:
- Death: shuts down the host cell and only does viron replications.
- Transformation: infection can induce oncogens resulting un uncontrolled and uninhibited cell growth.
- Latent infection: can sleep within the cell, making it clinically overt. varous factors can reactivate it later.
- Chronic Slow infection: can cause disease in many years, or decades, or indolent infection.
1-2 day incubation period.
Viral structure: spherical, with 8 segments on NEGATVIE stranded RNA put together with a protein called nucleocapsid protein (NP).
Orthomuxovirdae
outer proteins of influenza virus?
Outer proteins:
Hemaggultinin Activity (HA) - they attach to Silalic Acid receptors and cause heme-agglutination of RBC. needed for absorption in the upper respiratory tracts.
Neuraminidase (NA) - mucin is a part of the upper respiratory tract. NA cleaves neuramic acid and disrupts the mucin barrier, exposing the sialic acid binding sites beneath. NA then cleaves the sialic acid receptors when the virons are leaving the cells.
Influenza A vs B/C
Influenza A = mammals, Influenza B and C are in humans.
what is worse the flue or influenza?
who is at risk?
Influenza virus > The Flue; Pneumonia at risk groups, more severe risk groups.
define epidemic influenza
within the winter (Dec- Early March) is an outbreak in a city, state, or entire country. first sign is otitis media or pneumonia in children with secondary pneumonia in adults. this is followed by death in elderly and immunocompromised (chronic diseases).
high fever, chills (frank shaking chills), headache, malaise (feeling like shit), and myalgia (muscle aches)
the flu
dry cough, sore through, rhunorrhea (runny clogged nose), painful muscle aches, high fevers, and headaches set this apart from a mild cold.
URI
much more severe outbreaks. with common seconday infections: bacterial pneumonia, or otitis media (staphlococcus aureus, Haemophilus influenzae, or strepococcus pneumoniae.
Pandemic influenza
ab immunity, vaccines, and ativiral drugs that depend on the viral structure.
Neuroamindase inhibitors
slight changes in the viral coating
Antigentic drift
HUGE changes in the viral coating. causes pandemics due to not having any Abs to protect the humans from the infection.
antigenic shift
originally swine. caused the 1918 spanish flue
H1N1
Is avian virus emerged in 1997
H5N1
Complications of infuenza
Reye’s syndrome = head and liver disease due to giving a child asprin and not acetominophin.
Diagnostic tests for influenza (4)
Diagnostic tests:
- viral isolations. culture for genetis and antigenic analysis.
- detection of viral proteins: new one hour tests help guide the choice of antiviral agents.
- detection of viral RNA with PCR
- serological diagnostics: 4 fold increases in specific abs over 2 weeks.
(2-4 days incubation - Max is 8)
high fever, headache, myalgias, muscle aches, diarrhea, abdominal pain, vomiting, sore throat, rhinorrhea,
lower respiratory tract: cough, shortness of breath, production of sputum.
Acute respiratory distress syndrome: low blood oxygen levels, infiltrates in multiple parts of the lungs, no evidence of heart failure.
50% of people die and 90% of people under 15 years old die.
H5N1
Diagnosis for H5N1
Diagnosis H5N1: viral culture or reverse PCR of pharyngeal or nasal washings, or feces. Abs for H5 or a four fold in H5 titers.
- a single negative strand that isnt segmented.
- HA and NA are one glycoprotein.
- Fustion (F) protein to infect multinucleated giant cells.
- Lungs - replication in upper respiratory tract.
- Kids - most common infections.
- Viremia - viral infection that results in dissemination to distant sites.
Paramyxovirdae Characteristics
Parainfluenza virus and respiratory syncytial virus (RVS) are the main causes of what two things?
(1) Bronchiolitis, viral pneumonia, croup (in children),
(2) cold/flu in adults
stridor (wheezing)and a barking cough
Croup
Most common cause of pneumonia in children less than 6 months of age?
RVS (F protein and lacks HA and NA. not immune. )
upper and lower respiratory tract infections. primarily in young children and older adults. Second most common cause of lower respiratory tract infections. >1 year. bronchiolitis, croup, pneumonia. diagnose with PCR.
Matapneumovirus
parotits, testicular inflammation, upper respiratory tract and lymph nodes, PAROTID and TESTES (orchitis)
Mumps virus causes mumps
prodrome, koplik’s spots, rash, encephalitis
10 day incubation, 3-4 days prodrome (conjuctivitis, swelling of eye lids, photophobia, fever 105, hacking cough, rhinitis, and malaise), 1-2 days Koplick spots and small red lesions with blue center in the mouth, 6 days of a rash - head to toe
Measles (rubeola) virus > Measles
Complications Of Paramyxovirdae
pneumonia, eye damage, heart involvment, encephalitis is rare. spontaneous abortion, premature delivery, fetal death,
Subacute Sclerosing Panencephalitis (SSPE)
Subacute sclerosing panencephalitis (SSPE) due to the measles virus causing slowly progressing central nervous system disease, with mental deterioration and incoordination.
acute = will have a mild responce and will resolve. symptoms liek the fluw, with jaundice occuring two week slater due to high bilirubin.
AST (asparate aminotransferase) and ALT (alanine aminotransferase) will rise first. GGT (gammah-gluta,yl transpeptidase, and alkaline phosphase, and bilirubin will rise later due to peripheral intrahepatic cells dying.
Acute Hepatitis
bilirubin, GGT, and alkaline phosphate will rise first and the ALT and AST will rise second.
Gallstone
normally HBV. HCV, HDV is more difficult to diagnose leading to enlarged tender liver and mildly elevated liver function enzymes.
Chronic Hepatits
naked icosahedral capsid with POSITIVE single stranded RNA. Picornivaridae family meaning it is FECAL-ORAL route. spread by not washing your hands. 1 month incubation period (15-40 days). more frequent in young children. adults are more mild and without jaundice. death is rare. anti-HAV IgM means an active infection (peak at 2 months post jaundice) anti-HAV IgG means an old infection and no active disease. both will be negative during incubation or no infection.
HAV - hepatitis A Viradae
Will only replicate with the help of the HBV capsid. parenterally (IV drug use, blood transfusions, sexual contact.
superinfection = acute hepitiis in a person already with chronic hepatitis - increases mortality rate.
HDV
non-A, non-B hepatitis, 85% of acute continue to be chronic. leading cause of liver transplant in the USA today. enveloped icosahedral RNa virus in the flavivirus family. 3 structural genes and 5 nonstructural genes. genotype 1 in the most common in the USA, transmitted parentally primarilly through drug use. 6-12 well incubation. acute - asymptomatic, chronic = chronic hepatitis and cirrhosis
screen for anti-HCV Abs
HCV
non-A hepatitis. spread entericly (fecal-oral). endemic in asia, india, africa, and central america.
HEV
flavivirus family, transfusion and parental routes. not concluviely shown to cause liver disease.
HGV
with all body fluids. BIG AND BAD (42nm), icosahedral capsid and double stranded circular DNA, Dane particle is the intact virus that looks like a sphere, double stranded DNA with DNa polymerase enzyme. enveloped. Perental transmission (blood-blood).
Acute, Fulinant (severe acute hepititis with rapid liver destruction), Chronic hepatitis (carrier, chronic-persistent (smoldering), chrinic active (6-12 months), Co-infection with HDV.
HBsAg = disease (acute or chronic)
Anti-HbsAg = immunity/recovery with anti-HBeAg (envolope protein) - can deposit causing arthritis and skin/kidney damage.
IgM anti-HBcAg = new infection / Acute (Viral core)
IgG anti-HBcAg = old infection / Chronic
HbeAg = high infectivity (acute and chronie) (soluable core protein)
anti-HBeAg = low infectivity (chronic)
Complication - Primary Hepatocellular carcinoma and cirrhosis.
HBV
Clinical course of HIV infection
- normal CD4+ T cell counts are 1000 cells/ul blood. In HIV pts they decline 60 per year.
- CD4+ T cell count of 400-200 in about 7 years. symptoms: weight loss, fever, night sweats, adenopathy, sever athletes foot, oral thrush (canida), herpes zoster. bacterial infections especially Myobacterium tuberculosis become more common ad CD4+ count drop below 400!
- CD4+ Tcell count less than 200 (about 8 years). as the immune system fails, the serious opportunistic killers such as pneumocystic carnii pneumonia, cryptococcus neoformans, and toxoplasma gondii.
- CD4+ tell cell count is less than 50: at this point the immune system is completely down. mycobacterium aviun-intraqcellulare (MAC), normally causing infections in birds, causes disseminated disease in the AIDs pts, cytomegalovirus infections also rise as the count more fro 50 to zero.
Can develop a laten state within the snesory ganglia and migrate out with stress or AIDS. the members in the sub-family alpha have a cytopathis effect on cells, whish become multinucleated giant syncytial cells with intranuclear inclusion bidies. Held at bay by cell-mediated immunity. cytopathic effect: cell destruction by the seperation on the epithelium causing blisters. biopsy will reveal multinucleated giant cells and intranuclear inclusion bodies.
Herpesvirus (DNA)
clinical manifestations:
- Gingivostomatitis: swollen gums for 2 weeks.
- genital herpes: HSV1/2 will be painful or painless
- herpetic keratitis: THE MOST COMMON INFECTIOUS CAUSE OF CORNEAL BLINDNESS IN THE US.
- neonatal herpes: transplacental viral transfer
- Herpetic Whitlow: finger infection. most common in healthcare employees.
- Disseminated Herpes: immune compromised pt, willl infect the liver, lungs, and the GI.
- EncephalitisL HSV-1 is the most common cause of viral encephalitis. sudden fever and focal neurological abnormalities.
- reactivation: about 1/4 of infected people will reactivate in stressful situation.
Herpesviridae
TORCH
Herps is a TORCH infection that can cross the placental membrane.
Toxoplasmosis, Rubells, Cytomegalovirus, Herpes, HIV, and syphulis like infection.
what will be chicken pox and shingles?
Varicella-Zooster Virus (VZV)
superficial lesions, lesions usually no umbilicated, lesions at different stages of development, and lesions more on the trunk.
Chicken Pox
deep hard lesions, lesions oftun umbilicated (central depression), lesions at the same stage of development (Synchronous), lesions are more common on the extremities = deanse around the face and palms (centrifugal spread) and will ulcerate into a deeper lesion. (will burn and will most liekly be within a sensory dermatome)
Small Pox
CMV: infected cells beomce swollen.
4 infectious states:
- asymptomatic - most common
- congenital disease - TORCHES, micorencephaly, deafness, seizures, and other birth defects.
- cytomegalovirus mononucleosis: “mono” in young adults, kissing disease, blood smear will have atypical lymphocytes. blood will also have heterophile anti-body, aggulated with sheep RBC and can be used for rapid screening (Monospot test)
- CMV can reactive in immunosuppressed pts causing retinitis, pneumonia, disseminated infection and even death.
type of CMV with Bone marrow transplant
CMV pneumonitis
type of CMV with AIDS
CMV retinitis
Diagnosis CMV
buffy coat will show WBC with the virus, Antigen within the blood when the virus is replication, PCR when the virus is replication.
EBV causes?
Burkitt Lymphoma
Cause of small pox, erradicated in 1977, respiratort tract, skin lesions, death.
First vaccine by Edward Jenner from cow pox. worked becuase the virus becuase the vaccina virus is an arvirulent form of the poxivirdaw that can induce immunity. there are no animal reservoirs, every pt is obvious, virus isnt atmpyomatic. can be used for bioterrorism becuase most people are not immune anymore. can spread through droples and arosol
Pox virus
With bumps with a central dimple. similar to warts with benign hyperperfusion of epithelial cells. seen in AIDS pts.
Molluscum Contagiosum
causes human warts and cervical cancer
- type 16 and 18 casue cancer. vaccine prevents cancer in 98% of pts. 6 and 11 cause genital warts. warts are benign hyperproliferations of keratinized squamous epithelium.
Papovavirus - PA: Papilloma virus
Polyomavirus has two members ?
PO: Polyomavirus has two members BK and JC
ubiguitous, causes mile or asympomatic infection in children. symptomatic in immunocompromised causing nephritis and uretral stenosis in reanal transplant pts and hemorrhagic cystis in bone marrow transplant recipients.
Polyomavirus BK
in immunocompromised pts it causes progressive multifocal leukeoencephaly (PML) - CNS damage (memory loss, poor speech, and incoordination).
JC member of polyomarvirus
subgroup of papovavirus that does not infect humans.
VA: Simioan VAculating virus
causes upper respiratory tract infections. a den of coughing and sneezing children. can cause rhinitis, conjuctivitis, sore throat, and cough. sometimes progress to lower respiratory tract pneumonia in children.
Adenovirus
THE MOST COMMON RESPIRATORY ILLNESSES IN CHILDREN:
RSV, Metapneumonivirus, parainfluenza, rhinovirus, and adenovirus
enteric adenoviruses: cause diarrhea and is the second most common cause of endemic diarrheal illness in infants and chilrden across the world.
Is the smalles icosohdral virus with one stand od DNA. will cause erythemia infectiosum (5th disease) when they looked like they were slapped in the cheeks (rash) and fever.
Parvovirus
Transmitted by blood sucking arthropods causing fever, and encephalitis.
Arboviruses: Bunyaviridae, Togaviridae, Flaviviridae
(a) Alpha viruses that are mosquito born and cause encephalitis, inflammation of the brian, fever, headache, and altered level of conciounsness, with focal neurologic deficits.
(b) Rubovirus causes rubella.
Togaviridae
Three types of Alpha viruses:
WEE: western equine encephalitis
EEE: Eastern equine encephalitis
VEE: venezuelan equine encephalitis
Alpha virus that does not cause encephalitis. transmited by adea mosquetos, causes fever, rash, and JOINT PAINT AND SWELLING that will last longer then the fever and rash.
Chikungunya
only infects humans! mild febrile illness with a rash.
WILL CROSS THE PLACENTA!
contracted by respiratory secretions and prodrome of fever, lymphadenopathy, and flu symptoms. followed by maculopapular rash that spreads from the forhead > face> torso> extremities.
Rash WILL ONLY LAST 3 DAYS!
Rubovirus - Rubella
Congential defects in the first trimester: (due to chromosomal breakage and inhibition of mitosis)
(a) Heart: patent ductus, interventricular septal defects, pulmonary artery stenosis, etc.
(b) Eye: cataracts, chorioretinitis, etc.
(c) CNS: Mantal retardation, microcephaly, deafness.
not recommended to pregnant women to get the vaccine.
Congenital rubella
cause encephalitis, and named for geographic location. spread my mosquetoes and infect humans and birds.
Flaviviridiae
Second leading cause of epidemic viral encephalitis in the US?
St. Louis Encephalitis isthe second leading cause of epidemic viral encephalitis in the US!
made famous by the Panama Canal Project. one week incubation. fever, backache, naseua, vomiting. vaccination required for travel.
Yellow Fever
painful illnes. break-bone fever becuase of the severity of backache, muscle and joint pain, and severe headache. FAINFUL FEVER! 4 main sterotypes. SEROTYPE TWO will cause dengue hemorrhagic fever that causes hemorrhagic shock. especially in children) and mortality rate of almost 10%
Dengue Fever
Came to North Ameria in 1999. vector is a bird or mosqueto. can infect birds and horses and is lefthal. also spread by blood transfusions, transplacental to a fecus, breast milk, or lab accident.
clinical manifestations: most are asymptomatic. possible symptoms include headache, maculopapular rash, fatigue, weakness, difficulty concentrating, neuroinvasive dises: aceptic meningitis or frank encephalitis with dec level of conciousness or dramatic motor paresis or paralysis. polio like symptoms with ant spinal cord pathology. if there are sever clinical manifestations - prognosis is poor!
West Nile Virus
Diagnosis for West Nile?
Diagnosis:
1. culture with PCR
2. serum IgM with IgG in the same person for WNV. must have both!
3. cerebrospinal fluid with IgM for WNV. MOST SENSITIVE TEST!
4. four fold rise in serum antibody titers.
prevention = DEET
causesfever and encephalitis such as california encephalitis and Rift Vally Fever.
Bunyviridae
influenza like illness followed by sudden respiratory failure, leading to death. genus: hantavrius with hemorrhagic fever with renal failure in Asia and Europe. RODENT VECTOR! Deer mouse is the primary vector of Sin Nombre virus (no name virus).
Clinical manifestation: fever, cough, nausea, vomiting, heart and resp rate is RAPID, high WBC, LOW platlets, ELEVATED RBC.
Diagnosis with IgM and IgG Abs for Sin Nombre Virus. Intubation REQUIRED to increase O2 in blood.
Hantavirus Pulmonary Syndrome
members of the Picornaviridae family
Picornaviridae = the family all have similar structure and replication.
contains 4 genra: enterovirus, rhinovirus, hepatovirus (Hep A), and parachovirus.
infects peyers patches (fecal-oral) and motor neurons (paralytic poliomyelitis). improvments in sanitation have decreased the spread. chances of polimyelitis increases with age.
Spreads from tonsils> peyers patches> blood> BBB> anterior horn of the sinal cord.
Mild illness: asymptomatic or mild afibrile viral illness is more common.
Aseptic meningitis: fever and meningismus can develop but recovers in 1 week!
Paralytic poliomyelinitis: destroys presynaptic terminals leaving the horns. begins as mild febrile illness and then 5-10 days later the fever reoccurs, followed by meningismus, followed by flacid paralysis. the later more serious events occur when older than 15 years.
Poliovirus
Vaccines for Polio?
Two types of vaccines: inactivated polio vaccine is from killed viruses provokin the IgG ab responce. Oral polio vaccination is from attenuated poliovirus that can have an association with parylitic poliomyelitis.
paralysis and DEATH in mouse with extensive skeletal ms necrosis.
Herpangia: mild self limiting, fever, sore throat, small red-based vesicles over the back of the throat.
Hand, foot, and mouth syndrome - oral vesicles and lesions on hands and feet.
Coxachie A Viruses
less severe infection in mouse (organ damage to heart, breain, liver, pancrease and skeletal ms.
Pleurodynia: fever, headache, severe lower thorachic pain on breathing = respirator infection.
Myocarditis/Pericarditis: self limiting infection around the heart or more serious arrhythmias, cardiomopathy, heart failure.
Coxachie B viruses
asymptomatic or mild fibrile illness, respiratory symptoms, rashes, aseptic meningitis.
Coxachie A and B
asymptomatic, respiratory, rashes, aseptic meningitis, pericarditis.
Echovirus
VIRUSES THAT CAUSE THE “COLD”
Rhinovirus and Coronoviridae both cause the common cold. they are indistiguishable from eachother. 15% of adults are coronaviridae.
enveloped, single stranded RNA virus. SARS is an emerging infectious disease. no reservoir but there is a similar disease in bats.
SARS-like have been isolated in palm civets and raccoon dogs.
Primary mode of transmission is through direct or indirect contact of the mucus membreane (eyes, nose, mouth) with infectious respiratory droplets. more spreading by one person is a super-spreading event.
THE DEADLY SARS VIRUS (SARS-LIKE CORONAVIRUSES OR SARS-COV)
(2-10 days of incubation), fever, myalgias, chills, later develop dry cough, chest pain (pleurisy) and shortness of breath. FEW pts develop sore throat - CT has alveolar consolidations that can progress into adult ARDA. 8% dies from respiratory failure.
SARS Virus
Diagnosis of SARS
Reverse Transcriptase PCR of respiratory secretions, feces, urine, and lung biiiiopsy tissue, or seroconversion (Abs)
viruses that cause gastroenteritis are aquired by the fecal-oral route and usually prey on infants and young children, although outbreaks among adults do occur. how do these pts die?
DEATH BY DEHYDRATION
primarily infects young children and infants (indistiguishable)
Caliciviridae
Norwalk, Ohio elem school - diarrhea and vomitting.
Norwalk Virus
major cause of acute infectious diarrheal outbreaks like on cruise ships and Katrina. live attenuaded vaccine (RotaSheild) was launched in US but withdrawln due to an association with intussusception (inversion of the small into the large intestine). RotaTeq and Rotarix have been approved and are given orally.
Norovirus
periodic ourbreaks in infants, children and elderly.
Astrovirus
Bullet shaped, enveloped, helical symmetry nucleocapsids. rabies virus is the onyl one in the family that normally infects humans, but can infect all warm blood animals causing encephalitis, feerlessness, aggressivness, and disorientation.
When human is bit, it replicates within the wound for a few days (weeks, years). then migrates up the peripheral nerve’s axon to the CNA causing fatal encephalitis. NEGRI BODIES = PATHOGNOMONIC once there are clinical symptoms there is a rapid progression to death in 1-2 weeks.
Prodrome = infected person gets nonspecific fever, headache, sore throat, fatigue, nausea, and painful sensitive nerves around the wond. the muscle at the site will FASICULATE!
acute encephalitis = hyperactivity and agitation leading to confusion, meningismus, and even seizures = MADNESS!!
Classic brainsteam encephalitis = CN dysfunction and painful contractions or pharyngeal ms with swallowing (Hydrophobia) results in inability to swallow saliva and causes foaming of the mouth.
death = secondary to repiratory dysfunction. only two people have lived due to inducing a coma, and not giving the vaccine.
vaccination of dog is effective, cleaning the wound helps, antimals with symptooms should be captured and destroyed.
RHABDOVIRDAE and RABIES
heavy fatigue, crampy abdominal pain, hiccups, large bloody bowel movement, blood from nose and mouth with bloody diarrhea
Filo - filamentous shape of the RNA virus. both can be weaponized. spreads through direct contact with bodily fluids. however there are cases of nosocomial infectioins of health care workers in which airborne transmission could not be ruled out.
strict guildines for sheild protection, as well as droplet precausions for airborne possibilities.
epidemics are controlled due to limiting contact with bodily fluids, sterile needles, limiting lab blood work, peoper disposal of bodies, laundry.
no antiviral therapy, die due to hypotension from capillary leak, pts need intensive care and pharmacologic blood pressure support.
Filoviridae: Ebola
slower onset but the same course as filiviridae. main means of transmission is droplet, but airborne cannot be ruled out. these are treatable with high dose, IV ribaviran to reduce mortality.
Arenaviridae: Lassa Fever virus, and the 4 south american hemorrhagic fever viruses (Junun virus, Machupo virus, Guanarito virus, Sabia Virus).
will cause hemorrhagic fever. neither is tranmissible person to person but lab workers have been infected by aerosolization of specimens. Rift vally is treatable and yellow fever isnt.
Rift Valley Fever (family bunyaviridae) and yellow fever virus
How do viruses obtain energy?
they are energy-less, they float around until they come in contact with the appropriate cell.
