Lecture ONE, EXAM 3 Flashcards
(84 cards)
1
Q
What are the smallest of all microbes?
A
Viruses
2
Q
What can fit on the head of a pin?
A
500 million rhinoviruses (common cold) could fit on the head of a pin
3
Q
- Viruses are only alive and can multiple where?
- The cell they multiply in is called what?
- What is the purpose of viruses?
A
They are only alive and able to multiply inside the cells of other living things (can be outside of body for a little bit but needs to be inside)
* The cell they multiply in is called the host cell
* They only exist to make more viruses + make you sick
4
Q
What is the virus made up of? What can be additional?
A
Virus is made up of a core of genetic material, DNA or RNA surrounded by a protective coat called a capsid (made of protein)
* Sometimes the capsid has an additional spiky coat called the envelope (ex. COVID)
5
Q
How does the virus come into cells and what happens?
A
- The virus particle attaches to the host cell before penetrating it
- Then uses the host cells machinery to replicate its own genetic material
- Once replication done the virus particle leaves the host by either budding or and bursting out of the cell- called lysis
6
Q
- Where are viruses inert?
- They are unable to do what?
- What is an obligate intracellular parasite?
- What is virion?
A
- Viruses are inert outside the host cell
- They are unable to generate energy
- Obligate intracellular parasite, they fully depend on the complicated biochemical machinery of eukaryotic or prokaryotic cells
- A fully assembled infectious virus is called a virion (once inside the body)
7
Q
What are the classification of viruses we care about?
A
DNA, RNA, retrovirus
8
Q
Double-Stranded DNA Viruses:
* Large or small?
* What mostly makes up this group?
* Important what? (give examples)
* What are other viruses?
* Many can rely on what?
A
9
Q
What is the bacteria eater?
A
Bacteriophage
10
Q
Bacteriophage:
* Viruses that infect what?
* Composed of what?
* Where are they found?
* Harmless to who?
A
- Viruses that infect bacteria
- Composed of proteins and a DNA or RNA genome
- Bacteriophages are found everywhere but more commonly in the ocean
- Harmless to human cells
11
Q
How do bacteriophages work
A
- Inject their genome into the bacteria which disrupts the bacteria’s normal replication cycle
- The replicated viruses are then released, by lysis of the bacteria, and are free to infect new bacteria
12
Q
What is the bacteriophage life cycle?
A
13
Q
Eukaryotic Viruses
Viruses that can infect mammalian hosts can be subdivided into: (3)
A
- Bacteriophages: which infect prokaryotic cells
- Eukaryotic viruses: infect host and other eukaryotic cells
- Virus derived genetic elements: can incorporate into host chromosomes and result in the generation of infectious virus at a later date
14
Q
Eukaryotic viruses include what?
A
Eukaryotic viruses include a vast array of viruses that permanently infect the host and can exist for decades in asymptomatic individuals
* Locally or systemically
15
Q
What are the examples of eukaryotic viruses she gave us? (6)
A
16
Q
What does HSV 1+2, Varicella zoster virus, and epstein barr virus cause?
A
- Herpes simplex virus I and II—cold sores and genital herpes, respectively.
- Varicella zoster virus—chickenpox, shingles.
- Epstein–Barr virus—infectious mononucleosis, some cancers.
17
Q
What does HHV 6+7 cause? HHV 8?
A
- HHV 6 and HHV 7—infect children, fevers, rash, rare febrile seizures
- HHV 8—Kaposi’s sarcoma in AIDS patients
18
Q
Herpes virus Infections:
* How many known herpes viruses? How many infect only humans? list them
A
100 known herpes viruses, 8 routinely infect only humans - herpes simplex type 1 and 2, varicella zoster, cytomegalovirus, Epstein-Barr, HH6, HH7, Kaposi’s sarcoma
19
Q
HVI:
* Virus replicates initially where? Produces what? ⭐️ ⭐️⭐️⭐️⭐️⭐️⭐️⭐️⭐️⭐️⭐️
* Then what happens?
A
Virus replicates initially in epithelial cells producing a characteristic vesicle on an erythematous base
* Then it ascends along the sensory nerves to the dorsal root ganglia where after an initial period of replication, it establishes latency
* During reactivated infections the virus spreads distally from the ganglion to initiate new cutaneous and/or mucosal lesions
CAN DO SUPPRESSIVE THERAPY
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Q
Herpes virus Infections:
What does the virus contain?
A
The virus contains double stranded DNA located at its central core and surrounded by a capsid
21
Q
Herpes Simplex:
* HSV 1 vs 2?
* Unique characterisitc?
A
- HSV 1 transmission is primarily oral
- HSV 2 transmission is primarily genital
- Unique characteristic is their ability to establish latent infection
22
Q
Herpes simplex:
* What is well recongized?
* Stimuli observed to be associated with reactivation?
A
Reactivation of latent virus is a well recognized biologic phenomenon, but not one that is understood from a biochemical or genetic standpoint
* Stimuli observed to be associated with reactivation: stress, menstruation, and exposure to UV light (STRESS)
23
Q
What is the herpes simplex virus life cycle?
A
24
Q
Hep B:
* What type of virus?
* Is it an issue?
* Transmitted how?
* Any preventive txt?
A
- DNA virus
- Serious global healthcare problem - life threatening liver infection
- Transmitted via body fluids like blood, semen, and vaginal secretions
- Hep B vaccine
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* More than 95% of immunocompetent adults infected with HBV can do what?
* What happens when you cannot?
More than 95% of immunocompetent adults infected with HBV can clear the infection spontaneously (below if cannot clear it)
* **Acute infection**: Anicteric hepatitis, icteric hepatitis, fulminant hepatitis
* **Chronic infection**: Asymptomatic, chronic hepatitis, cirrhosis and hepatocellular carcinoma
| Ammonia and clotting factors are affected
no real txt
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With Hep B:
What does the history taking emphasize?
History taking should emphasize the social history, including sexual practices (e.g., unprotected, same-sex, etc.), illicit drug use, profession (e.g., healthcare worker, sex worker), and living arrangements (i.e., within the same household as a patient with HBV infection).
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What are high risk groups for hep b?
(i.e., healthcare workers, IV substance abuse patients, etc.) or those from highly endemic areas may warrant testing. Those with certain mental illnesses like bipolar disorder, schizophrenia, or manic disorder are at an increased risk for contracting HBV infection during manic states within which one may participate in risky sexual behaviors, including unprotected sex.
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For hep B, the physical exam should also assess what?
Physical examination should also assess for stigmata of chronic liver disease, including jaundice, ascites, hepatomegaly, splenomegaly, palmar erythema, Dupuytren contractures, spider nevi, gynecomastia, caput medusa, and hepatic encephalopathy which suggests portal hypertension and cirrhosis
## Footnote
Dupuytren contractures: A gradual thickening and tightening of tissue under the skin in the hand-> POPPING
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Adenovirus:
* What type of virus?
* How many serologic types? How many for humans?
* Spreads via what?
* Causes what?
* Double stranded DNA virus common in animals and humans
* 100 different serologic types of adenovirus, 49 that can infect humans
* Spreads via aerosolized droplets, direct inoculation to the conjunctiva, exposure to infected tissue, blood and fecal-oral route
* Causes upper respiratory tract infections and conjunctivitis
| COMMON COLD-> COULD ALSO BE RHINOVIRUS
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Poxvirus:
* What type of virus? Assembles where?
* What does it cause?
* Has a genera called what? What does it cause?
* Dual stranded DNA virus that replicates and assembles entirely in the cytoplasm (independent of the nucleus)
* Famous for causing Smallpox
* Also has a genera that is known as mulluscipox which causes molluscum contagiosum
| VACCINATED AGAINST IT
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Rotavirus:
* Leading cause of what?
* Due to vaccine, norovius has exceeded what?
* Traditionally thought of as what?
* Leading cause of severe gastroenteritis in children less than 5 years of age
* Due to vaccine, norovirus has exceeded rotavirus in leading cause of acute viral gastroenteritis
* Traditionally thought of as a winter disease
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Rotavirus:
* Some safety with what?
* What type of virus? Named for what?
* Transmission how?
* Causes what?
* Some safety with vaccine, but still with more than 200k deaths worldwide per year
* Double stranded RNA virus – named for its classic ”wheel-shaped” appearance.
* Transmission occurs through fecal to oral route
* Causes severe diarrhea resulting in dehydration
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Rotavirus:
* What are the modes of transmission? (3)
* Ingestion of contaminated food and water
* Directly from feces contaminated fingers
* Occasionally by droplet infection
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Rotavirus:
* Who is mostly affected?
* Adults are infected how?
* Incubation period?
* Children below 5 years are mostly affected
* Adults are infected by contact with pediatric cases
* Incubation 2-3 days
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Rotavirus:
* What is the viral encoded toxin?
* What does it disrupt?
* The acute infection and diarrhea normally resolves within what?
* Viral encoded toxin: early profuse, secretory diarrhea is caused by enterotoxin, NSP4.
* Disruption of intestinal epithelium due to virus replication
* The acute infection and diarrhea normally resolves within 7 days in immunocompetent hosts
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Poliovirus:
Mentioned where?
Mentioned in ancient Egyptian painting and carvings, 1403 to 1365 BC depict children with deformed limbs, walking with sticks
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Poliovirus:
* Clinical features?
* Disease has been associated with what?
* What eradicated the disease?
* Clinical features are varied ranging from mild cases of respiratory illness, gastroenteritis to severe forms of paralysis
* Disease has been associated with crippling deformities
* Vaccine eradicated the disease: By 1961 only 161 cases were recorded
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Poliovirus:
* How does it enter our body?
* Spread how? Rapid spread where?
* Poliovirus enters the oropharynx and multiples locally in the tonsils, lymphnodes of the neck, Peyer patches and small intestines
* Spread is fecal-oral route-> Rapid spread in areas with poor sanitation
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Zika Virus:
* What type of virus?
* Transmitted by what?
* Infection symptoms?
* Single stranded RNA virus
* Transmitted by the bite of a female Aedes aegypti and Aedes albopictus mosquitos
* Person to person (sexual contact), blood transfusion, organ transplantation and maternal-fetal vertical transmission
* Most patients with acute Zika virus infections are either asymptomatic (60- 80%) or have only mild symptoms (rash, conjunctivitis, fever, headache)
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Zika Virus:
* Infection during pregnancy can cause what?
Zika virus infection during pregnancy is the cause of a variety of congenital disabilities, including microencephaly and other brain abnormalities
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Hep A:
* What type of virus?
* Replicates where?
* Commonly transmitted through what? what happens when ingested?
* Single stranded RNA virus
* Replicates primarily within hepatocytes
* Commonly transmitted through the oral-fecal route via exposure to contaminated food, water, or close physical contact with an infectious person
* Once ingested orally, the virus is taken up from the gastrointestinal tract
* HAV particles are carried to membrane of the hepatocyte via the portal circulation
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Hep A:
* does not cause what?
* What type of illness? May develop what?
* Hep A rates have what?
HAV does not cause chronic liver disease, unlike HepB and HepC
Self limited illness - nausea, vomiting, abdominal pain, fatigue, malaise, poor appetite, fever (GI SYMPTOMS BUT REPICATE IN LIVER)
* May develop dark urine and pale stools, followed by jaundice and pruritis
HAV rates have decreased due to improvements in public healthcare policies, sanitation, and vaccination
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What are the symptoms of hep A
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What is the One of the most common viruses to infect children worldwide?
Respiratory Syncytial Virus (RSV)
* Infects 90% of children within the first 2 years of life and frequently re-infects older children/adults
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Respiratory Syncytial Virus (RSV):
* What does it cause?
* What population is it the most dangerous?
* What type of virus?
* Causes upper respiratory infection: children: bronchiolitis (lower respiratory tract with small airway obstruction)
* In children, the most dangerous respiratory infection.
* RNA virus
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Respiratory Syncytial Virus (RSV):
* What does it lack?
* Spreads how?
* Lack of long term immunity, making reinfection frequent
* Spread person to person via respiratory droplet – rapidly spreads into the respiratory trac
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RSV:
* What are the clinical manifestation?
* What is the treatment?
Clinical manifestations.
* Acute onset of fever, cough, rhinitis, nasal congestion.
* May progress quickly to severe respiratory distress.
Treatment, prevention, and control.
* Rapid immunologic tests.
* Fluid replacement and fever reducers.
* Palivizumab given as a preventative measure to premature infants.
* Isolation, protective clothing, and hand washing
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Phabdoviridae: Rabies virus
* Old or new disease?
* What type of virus?
* Primarily transmitted how? What are other ways?
* One of the oldest known disease in history with cases dating back to 4000 years ago
* RNA virus
* Primarily transmitted by bites of infected animals.
* Also transmitted by aerosols in caves where bats roost or by contamination of scratches, abrasions, open wounds, or mucous membranes with saliva of infected animals.
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Rhabdoviridae—Rabies virus
* How many cases per year in US?
* What does it cause?
* Fewer than 10 cases per year
* Causes encephalitis
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Rhabdoviridae—Rabies virus.
* What are the clinical manifestations?
* Begins 2 to 16 weeks after exposure.
* Pain at wound site, anxiety, irritability, depression, fatigue, loss of appetite, fever, and sensitivity to light and sound.
* Quickly progresses to paralysis.
* Death via destruction of brain regions that regulate breathing
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Filoviridae—Ebola virus
* What type of virus?
* Common to infect who? Causes what?
* What is the natural host?
* Member of single-stranded RNA family called the Filoviridae. (Derived from: ”filum” meaning thread- has characteristic twisted thread shape)
* Most common to infect humans and primates, causing highly fatal hemorrhagic fever
* Fruit bats belonging to the Pteropodidae family serve as the natural host for the Ebola virus
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Ebola virus:
* What are the symptoms
* Transmission from what?
* How is it killed?
* What is txt?
* Symptoms: hemorrhagic fever - but also malaise, headache, diarrhea or vomiting. Can progress to multi organ system failure leading to shock and death
* Transmission from direct contact with Ebola victim, body fluids or clinical samples.
* Virus is very resilient, killing it takes high doses of gamma irradiation UV light or 30-60 min of intense heat (140 degrees Fahrenheit)
* Supportive therapy; no treatment available (but some success using convalescent sera and antibody cocktails).
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Measles:
* Affect who?
* Bad part?
* Causes what?
* Diagnosis can be made with what?
* Virtually affected all children before they reached adolescence
* Bad part: complications of the disease were serious – croup, hemorrhagic rash, parainfectious encephalitis, etc.
* Causes exanthematous rash
* Diagnosis can be made with detection of antibodies
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Mumps:
* Not considered what?
* bad part?
* Not considered a globally devastating disease
* Bad part: complications still severe: aseptic meningitis, meningoencephalitis, deafness
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When is the MMR vaccine given?
MMR vaccine given at age 15 months and 4 years old
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Influenza virus:
* How many types? What causes human infection?
4 types of influenza
* A, B, C, and D
* Influenza types A and B cause human infection annually during the epidemic season
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Influenza virus:
* Influenza A has several subtypes according to what?
Influenza A has several subtypes according to the combination of hemagglutinin and neuraminidase proteins expressed on the surface of the virus
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What do hemagglutinins, neuraminidase, and influ A do?
* Hemagglutinin adheres to the epithelial cells in the respiratory tract allowing for the progression of the infection
* Neuraminidase cleaves the bond that holds the virus together and helps to spread the virions
* Influenza A viruses are characterized by the H and N types such as H1N1 and H3N2
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What is the life cycle of influenza?
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Coxsackie virus:
* What type of virus?
* Part of what?
* In the family with who?
* Coxsackievirus A type 16 and enterovirus A71 are what?
* Non-enveloped single stranded RNA virus
* Multiple types that cause a variety of diseases, part of the Enterovirus family
* In the family with the poliovirus
* Coxsackievirus A type 16 and enterovirus A71 are the serotypes most commonly implicated as causative agents causes hand, foot, and mouth disease
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Coxsackie virus:
* occurs with what?
* What happens after ingestion of the virus?
* Occurs with oral ingestion of the shed virus from the GI or upper respiratory tract of infected hosts via vesicle fluid or oral secretions
* After ingestion the virus replicates in the lymphoid tissue of the lower intestine and the pharynx and spread to regional lymph nodes
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Coxsackie virus:
* Commonly affects who?
* Outbreaks where?
* What tests are Available ?
* Commonly affects children, but can affect adults
* Outbreaks in daycares, summer camp
* There are serologic tests, but diagnosis made by physical exam and suspicion
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Coronavirus:
* Large family of what?
* What is the main type?
* What type of virus?
* The virus has what? What does that allow?
* Large family of respiratory viruses that includes COVID-19, Middle East Respiratory Syndrome (MERS), and Severe Acute Respiratory Syndrome (SARS)
* SARS-Co-V-2 (severe acute respiratory syndrome coronavirus 2 – also known as COVID 19
* Single stranded RNA virus
* The virus has a spiked protein that gains entry into the host cells by binding the SARS-CoV-2 spike to the **ACE2 receptors** in the respiratory epithelium
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SARS-CoV-2 spike binds where?
the ACE2 receptors in the respiratory epithelium
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COVID:
* What is the early phase and late phase?
**Early phase**: viral replication results in direct virus-mediated tissue damage
**Late phase**: infected host cells trigger an immune response by recruiting T lymphocytes, monocytes, and neutrophils
* Cytokines like TNF alpha, IL-1, IL-6, IL-8, IL-12 are released
* In severe cases it can cause a cytokine storm – an over activation of the immune system and high levels of cytokines- local and systemic inflammatory response
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In serve cases of COVID transmission, what can happen?
In severe cases it can cause a cytokine storm – an over activation of the immune system and high levels of cytokines- local and systemic inflammatory response
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COVID:
* Adapts with what?
* First reported where?
* Primary mode of transmission?
* Adapts with genetic evolution and developing mutations
* First reported in Wuhan, China is Dec 2019, thought to have been from zoonotic transmission
* Rapidly disseminated worldwide- more than 6 million deaths
* Primary mode of transmission is via exposure to respiratory droplets carrying infectious virus from close contact
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KNOW THE PICTURE OF COVID
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Retrovirus:
* What does it convert?
* dsDNA integrates into what?
* Convert ssRNA into dsDNA using reverse transcriptase.
* dsDNA integrates into host cell genome and serves as template for mRNA synthesis and genome synthesis
## Footnote
HIV is an example
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HIV:
* What type of virus?
* Causes what?
* Chronic HIV infection?
* Enveloped retrovirus that contains 2 copes of a single stranded RNA genome
* Causes AIDS (acquired immunodeficiency syndrome) at the late stages or when HIV is not properly managed
* Chronic HIV infection, cannot be cured
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How is HIV classified?
How many people are affected?
Classified into HIV-1 and HIV-2
* HIV-1 is more globally expanded and virulent (originated in Central Africa)
* HIV-2 is much less virulent and comes from West Africa
Estimated to affect 36.7 million worldwide as of 2016
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What is the pathophysiology of HIV?
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What is the HIV life cycle?
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What are chronic HIV infection without AIDS?
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* How is aids defined?
* AIDS defining conditions relate to what?
* AIDS is defined as a CD4 cell count <200 cells/microL or the presence of any AIDS- defining condition regardless of the CD4 cell count.
* AIDS-defining conditions relate to those opportunistic illnesses and malignancies that occur more frequently or more severely as a result of immunosuppression
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What are infections with AIDS?
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HIV:
* What is used to treat it?
* Used in what?
* Antiretrovirals are used to treat HIV/AIDS
* Used in various combinations referred to as highly active retroviral therapy (HAART)
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HIV:
What are the antiretroviral agents?
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* All patients with HIV, regardless of what level of CD4 should be what?
* CD4 count greater than 500 tend to have what?
* CD4 count less than 200 have what?
* CD4 count greater than 200 but less than 500 do not have what? But what can happen?
* All patients with HIV, regardless of what level of CD4 should be started on HAART (for life)
* CD4 count greater than 500 tend to have a good quality of life with a lifespan within 4 years of someone without HIV
* CD4 count less than 200 have AIDS and are susceptible to opportunistic infections – have a lifespan of 2 years if started on HAART
* CD4 count greater than 200 but less than 500 do not have AIDS but can develop chronic infections as well as noninfectious conditions such as candidiasis, herpes simplex/zoster, etc.
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