Viruses

Viruses US Medical PG Question 1: An HIV-positive 48-year-old man comes to the emergency department because of a 3-month history of recurrent, painful mouth ulcers. This time, the pain is so severe that the patient cannot eat. He has a history of a seizure disorder but currently does not take any medications. He appears very ill. His temperature is 39.0°C (102.2°F). Physical examination shows numerous vesicular ulcerations on the lips and sloughing of the gums, buccal mucosa, and hard palate. Genetic analysis of the pathogen isolated from the lesions shows a mutation in a gene encoding viral phosphotransferases. Which of the following drugs is the most appropriate treatment?

• A. Acyclovir
• B. Famciclovir
• C. Cidofovir
• D. Ganciclovir
• E. Foscarnet (Correct Answer)

Viruses Explanation: ***Foscarnet*** - The presence of **recurrent, painful vesicular ulcerations** in an HIV-positive patient, especially with **gingivostomatitis-like symptoms** (sloughing gums, buccal mucosa), points to a severe **herpes simplex virus (HSV) infection**, likely resistant to nucleoside analogues given the **phosphotransferase mutation**. - **Foscarnet** is a pyrophosphate analog that directly inhibits viral DNA polymerase without requiring phosphorylation by viral thymidine kinase, making it effective against **acyclovir-resistant HSV** strains, which often develop resistance via mutations in viral phosphotransferases or thymidine kinase. *Acyclovir* - **Acyclovir** is a nucleoside analog that requires phosphorylation by viral thymidine kinase (a phosphotransferase) to become active. - A **mutation in viral phosphotransferases** would render the virus resistant to acyclovir, making it an ineffective treatment. *Famciclovir* - **Famciclovir** is a prodrug of penciclovir, which is also a nucleoside analog that requires phosphorylation by viral thymidine kinase for activation. - Similar to acyclovir, a **mutation in viral phosphotransferases** would lead to resistance and make famciclovir ineffective. *Cidofovir* - **Cidofovir** is a nucleotide analog that does not require phosphorylation by viral enzymes for its initial activation. - While it can be effective against some resistant strains, **foscarnet is generally preferred** for severe, resistant HSV infections as cidofovir is primarily used for **CMV retinitis** and is associated with significant nephrotoxicity. *Ganciclovir* - **Ganciclovir** is a nucleoside analog primarily used for **CMV infections**, and it also requires phosphorylation by viral kinases for activation. - It is not the first-line treatment for HSV, and the **phosphotransferase mutation** would likely confer resistance to ganciclovir as well.

Viruses US Medical PG Question 2: A scientist in Boston is studying a new blood test to detect Ab to the parainfluenza virus with increased sensitivity and specificity. So far, her best attempt at creating such an exam reached 82% sensitivity and 88% specificity. She is hoping to increase these numbers by at least 2 percent for each value. After several years of work, she believes that she has actually managed to reach a sensitivity and specificity even greater than what she had originally hoped for. She travels to South America to begin testing her newest blood test. She finds 2,000 patients who are willing to participate in her study. Of the 2,000 patients, 1,200 of them are known to be infected with the parainfluenza virus. The scientist tests these 1,200 patients’ blood and finds that only 120 of them tested negative with her new test. Of the following options, which describes the sensitivity of the test?

• A. 82%
• B. 86%
• C. 98%
• D. 90% (Correct Answer)
• E. 84%

Viruses Explanation: ***90%*** - **Sensitivity** is calculated as the number of **true positives** divided by the total number of individuals with the disease (true positives + false negatives). - In this scenario, there were 1200 infected patients (total diseased), and 120 of them tested negative (false negatives). Therefore, 1200 - 120 = 1080 patients tested positive (true positives). The sensitivity is 1080 / 1200 = 0.90, or **90%**. *82%* - This value was the **original sensitivity** of the test before the scientist improved it. - The question states that the scientist believes she has achieved a sensitivity "even greater than what she had originally hoped for." *86%* - This value is not directly derivable from the given data for the new test's sensitivity. - It might represent an intermediate calculation or an incorrect interpretation of the provided numbers. *98%* - This would imply only 24 false negatives out of 1200 true disease cases, which is not the case (120 false negatives). - A sensitivity of 98% would be significantly higher than the calculated 90% and the initial stated values. *84%* - This value is not derived from the presented data regarding the new test's performance. - It could be mistaken for an attempt to add 2% to the original 82% sensitivity, but the actual data from the new test should be used.

Viruses US Medical PG Question 3: A 27-year-old woman who recently emigrated from Brazil comes to the physician because of fever, fatigue, decreased appetite, and mild abdominal discomfort. She has not seen a physician in several years and her immunization status is unknown. She drinks 2 alcoholic beverages on the weekends and does not use illicit drugs. She is sexually active with several male partners and uses condoms inconsistently. Her temperature is 38°C (99.8°F). Physical examination shows right upper quadrant tenderness and scleral icterus. Serology confirms acute infection with a virus that has partially double-stranded, circular DNA. Which of the following is most likely involved in the replication cycle of this virus?

• A. Adhesion of virus to host ICAM-1 receptor
• B. Cleavage of gp160 to form envelope glycoprotein
• C. Bacterial translation of viral DNA
• D. Transcription of viral DNA to RNA in the cytoplasm
• E. Reverse transcription of viral RNA to DNA (Correct Answer)

Viruses Explanation: ***Reverse transcription of viral RNA to DNA*** - The description of a virus with **partially double-stranded, circular DNA** that causes acute infection with fever, fatigue, and **scleral icterus** points to **Hepatitis B virus (HBV)**. - HBV is a **hepadnavirus** with a unique replication strategy: despite being a DNA virus, it replicates through an **RNA intermediate** (pregenomic RNA). - The virus uses **reverse transcriptase** to synthesize DNA from this RNA template within the nucleocapsid—making it the only DNA virus that uses reverse transcription in its replication cycle. *Adhesion of virus to host ICAM-1 receptor* - The **intercellular adhesion molecule 1 (ICAM-1) receptor** is primarily used by viruses like **rhinovirus** for entry into host cells, which is not characteristic of HBV. - HBV primarily uses the **sodium taurocholate co-transporting polypeptide (NTCP)** as its entry receptor on hepatocytes. *Cleavage of gp160 to form envelope glycoprotein* - **gp160** is a precursor protein of the **HIV envelope glycoprotein**, which is cleaved into gp120 and gp41, essential for HIV entry. - This process is specific to **retroviruses** like HIV and is not involved in HBV replication. *Bacterial translation of viral DNA* - Viruses, including HBV, replicate within **eukaryotic host cells** and utilize the host cell's machinery for replication, transcription, and translation. - **Bacterial translation** is irrelevant to viral replication in human hosts. *Transcription of viral DNA to RNA in the cytoplasm* - While transcription of viral DNA to RNA does occur in HBV, it primarily takes place in the **nucleus** of the host hepatocyte, not the cytoplasm. - The resulting pregenomic RNA is then exported to the cytoplasm for **reverse transcription** within newly assembled nucleocapsids.

Viruses US Medical PG Question 4: A 30-year-old forest landscape specialist is brought to the emergency department with hematemesis and confusion. One week ago she was diagnosed with influenza when she had fevers, severe headaches, myalgias, hip and shoulder pain, and a maculopapular rash. After a day of relative remission, she developed abdominal pain, vomiting, and diarrhea. A single episode of hematemesis occurred prior to admission. Two weeks ago she visited rainforests and caves in western Africa where she had direct contact with animals, including apes. She has no history of serious illnesses or use of medications. She is restless. Her temperature is 38.0℃ (100.4℉); the pulse is 95/min, the respiratory rate is 20/min; and supine and upright blood pressure is 130/70 mm Hg and 100/65 mm Hg, respectively. Conjunctival suffusion is noted. Ecchymoses are observed on the lower extremities. She is bleeding from one of her intravenous lines. The peripheral blood smear is negative for organisms. Filovirus genomes were detected during a reverse transcription-polymerase chain reaction. The laboratory studies show the following: Laboratory test Hemoglobin 10 g/dL Leukocyte count 1,000/mm3 Segmented neutrophils 65% Lymphocytes 20% Platelet count 50,000/mm3 Partial thromboplastin time (activated) 60 seconds Prothrombin time 25 seconds Fibrin split products positive Serum Alanine aminotransferase (ALT) 85 U/L Aspartate aminotransferase (AST) 120 U/L γ-Glutamyltransferase (GGT) 83 U/L Creatinine 2 mg/dL Which of the following is the most appropriate immediate step in management?

• A. Esophagogastroduodenoscopy
• B. Postexposure vaccination of close contacts
• C. Parenteral artesunate plus sulfadoxine/pyrimethamine
• D. Use of N95 masks
• E. Intravenous fluids and electrolytes (Correct Answer)

Viruses Explanation: ***Intravenous fluids and electrolytes*** - The patient presents with **orthostatic hypotension**, internal bleeding (hematemesis, ecchymoses), and deranged renal function (elevated creatinine). These indicate significant **fluid loss** and potential **hypovolemic shock**, making immediate fluid resuscitation critical. - **Ebola virus disease** (indicated by the travel history, symptoms, and positive filovirus genomes) often leads to severe dehydration due to fluid loss from vomiting, diarrhea, and internal bleeding, necessitating aggressive fluid and electrolyte replacement as a cornerstone of supportive care. *Esophagogastroduodenoscopy* - While the patient has hematemesis, her overall clinical picture with **severe coagulopathy** (elevated PT/aPTT, low platelets, positive fibrin split products) and **multisystem involvement** suggests a systemic bleeding disorder rather than a focal upper GI bleed that would be the primary target of an EGD. - Performing an invasive procedure like EGD in a patient with severe coagulopathy and a highly contagious disease like Ebola (implied by filovirus detection) carries significant risks and is not the most immediate priority compared to stabilizing vital signs and correcting fluid deficits. *Postexposure vaccination of close contacts* - This is a crucial public health measure for **Ebola virus disease** but is a secondary step in management focused on prevention for others, not the immediate stabilization or treatment of the acutely ill patient. - While important, it does not address the patient's immediate, life-threatening symptoms of hypovolemia, bleeding, and organ dysfunction. *Parenteral artesunate plus sulfadoxine/pyrimethamine* - This regimen is an antimalarial treatment. While the patient traveled to Western Africa, her symptoms and the detection of **filovirus genomes** rule out malaria as the primary diagnosis requiring this specific treatment. - Administering antimalarials would delay appropriate supportive care for Ebola virus disease and is not indicated given the specific viral diagnosis. *Use of N95 masks* - **N95 masks** are important for healthcare worker protection given the patient's symptoms and confirmed filovirus. However, the question asks for the most appropriate *immediate step in management* of the patient's condition. - While infection control is paramount, providing immediate direct patient care like fluid resuscitation takes precedence for the patient's survival over PPE considerations, assuming adequate PPE is already being donned by healthcare providers.

Viruses US Medical PG Question 5: An investigator studying viral replication isolates the genetic material of an unidentified virus strain. After exposing a cell culture to the isolated, purified viral genetic material, the cells begin to produce viral polymerase and subsequently replicate the viral genome. Infection with the investigated strain is most likely to cause which of the following conditions?

• A. Rotavirus infection
• B. Poliomyelitis (Correct Answer)
• C. Hepatitis B
• D. Rabies
• E. Influenza

Viruses Explanation: ***Poliomyelitis*** - The isolation of **purified viral genetic material** directly leading to viral protein production (polymerase) and genome replication indicates the virus has an **RNA genome that can directly serve as mRNA**. - **Poliovirus** is a **positive-sense single-stranded RNA (+ssRNA) virus**, meaning its genome can immediately be translated by host ribosomes upon entry, acting like mRNA. *Rotavirus infection* - Rotavirus is a **double-stranded RNA (dsRNA) virus** and requires its own **RNA-dependent RNA polymerase** to synthesize mRNA before protein production and genome replication can occur. - Its purified genetic material alone would not directly lead to viral protein synthesis in the absence of viral enzymes. *Hepatitis B* - Hepatitis B virus (HBV) is a **DNA virus** and replicates through an **RNA intermediate** via **reverse transcriptase**. - Its genetic material cannot directly initiate the production of viral polymerase or genome replication without complex cellular machinery and viral enzymes. *Rabies* - Rabies virus is a **negative-sense single-stranded RNA (-ssRNA) virus**, which means its genome cannot be directly translated into protein. - It requires its own **RNA-dependent RNA polymerase** to first synthesize complementary positive-sense mRNA strands. *Influenza* - Influenza virus is also a **negative-sense single-stranded RNA (-ssRNA) virus**. - Like rabies, it carries its own **RNA-dependent RNA polymerase** to transcribe its genome into mRNA before protein synthesis can begin.

Viruses US Medical PG Question 6: You are seeing a 4-year-old boy in clinic who is presenting with concern for a primary immune deficiency. He has an unremarkable birth history, but since the age of 6 months he has had recurrent otitis media, bacterial pneumonia, as well as two episodes of sinusitis, and four episodes of conjunctivitis. He has a maternal uncle who died from sepsis secondary to H. influenza pneumonia. If you drew blood work for diagnostic testing, which of the following would you expect to find?

• A. Abnormally low number of T cells
• B. Abnormally high number of B cells
• C. Elevated immunoglobulin levels
• D. Abnormally low number of B cells (Correct Answer)
• E. Abnormally high number of T cells

Viruses Explanation: ***Abnormally low number of B cells*** - The recurrent bacterial infections (otitis media, pneumonia, sinusitis, conjunctivitis) and the family history of death from *H. influenza* pneumonia suggest a **primary B-cell immunodeficiency**, such as **X-linked agammaglobulinemia (XLA)**. - In XLA, there is a block in B-cell development, leading to a profound absence of mature B cells and immunoglobulins. *Abnormally low number of T cells* - This would point towards a **T-cell immunodeficiency** or a **combined immunodeficiency**, typically presenting with opportunistic infections, viral, or fungal infections, rather than predominantly bacterial infections. - Examples include **Severe Combined Immunodeficiency (SCID)**, which often presents earlier and more severely. *Abnormally high number of B cells* - This is not characteristic of a primary immunodeficiency with recurrent bacterial infections; rather, it might be seen in certain autoimmune conditions or lymphoproliferative disorders. - **High B cell counts** generally imply a functioning humoral immune system, which contradicts the infectious history. *Elevated immunoglobulin levels* - This finding would generally indicate a **functioning humoral immune response**, possibly due to chronic infection or an inflammatory process, but not a primary B-cell immunodeficiency causing recurrent bacterial infections. - In conditions like **Common Variable Immunodeficiency (CVID)**, some immunoglobulin levels might be normal, but often key classes (like IgG, IgA, or IgM) are low. *Abnormally high number of T cells* - This finding is generally not associated with the pattern of recurrent bacterial infections described, which strongly points to a **humoral (antibody) deficiency**. - **Elevated T cells** could be seen in some autoimmune conditions or certain viral infections, but not typically in a primary immunodeficiency characterized by recurrent bacterial infections.

Viruses US Medical PG Question 7: A 28-year-old male presents to his primary care physician with complaints of intermittent abdominal pain and alternating bouts of constipation and diarrhea. His medical chart is not significant for any past medical problems or prior surgeries. He is not prescribed any current medications. Which of the following questions would be the most useful next question in eliciting further history from this patient?

• A. "Does the diarrhea typically precede the constipation, or vice-versa?"
• B. "Is the diarrhea foul-smelling?"
• C. "Please rate your abdominal pain on a scale of 1-10, with 10 being the worst pain of your life"
• D. "Are the symptoms worse in the morning or at night?"
• E. "Can you tell me more about the symptoms you have been experiencing?" (Correct Answer)

Viruses Explanation: ***Can you tell me more about the symptoms you have been experiencing?*** - This **open-ended question** encourages the patient to provide a **comprehensive narrative** of their symptoms, including details about onset, frequency, duration, alleviating/aggravating factors, and associated symptoms, which is crucial for diagnosis. - In a patient presenting with vague, intermittent symptoms like alternating constipation and diarrhea, allowing them to elaborate freely can reveal important clues that might not be captured by more targeted questions. *Does the diarrhea typically precede the constipation, or vice-versa?* - While knowing the sequence of symptoms can be helpful in understanding the **pattern of bowel dysfunction**, it is a very specific question that might overlook other important aspects of the patient's experience. - It prematurely narrows the focus without first obtaining a broad understanding of the patient's overall symptomatic picture. *Is the diarrhea foul-smelling?* - Foul-smelling diarrhea can indicate **malabsorption** or **bacterial overgrowth**, which are important to consider in some gastrointestinal conditions. - However, this is a **specific symptom inquiry** that should follow a more general exploration of the patient's symptoms, as it may not be relevant if other crucial details are missed. *Please rate your abdominal pain on a scale of 1-10, with 10 being the worst pain of your life* - Quantifying pain intensity is useful for assessing the **severity of discomfort** and monitoring changes over time. - However, for a patient with intermittent rather than acute, severe pain, understanding the **character, location, and triggers** of the pain is often more diagnostically valuable than just a numerical rating initially. *Are the symptoms worse in the morning or at night?* - Diurnal variation can be relevant in certain conditions, such as inflammatory bowel diseases where nocturnal symptoms might be more concerning, or functional disorders whose symptoms might be stress-related. - This is another **specific question** that should come after gathering a more complete initial picture of the patient's symptoms to ensure no key information is overlooked.

Viruses US Medical PG Question 8: Two viruses, X and Y, infect the same cell and begin to reproduce within the cell. As a result of the co-infection, some viruses are produced where the genome of Y is surrounded by the nucleocapsid of X and vice versa with the genome of X and nucleocapsid of Y. When the virus containing genome X surrounded by the nucleocapsid of Y infects another cell, what is the most likely outcome?

• A. Virions containing genome Y and nucleocapsid Y will be produced
• B. No virions will be produced
• C. Virions containing genome X and nucleocapsid Y will be produced
• D. Virions containing genome Y and nucleocapsid X will be produced
• E. Virions containing genome X and nucleocapsid X will be produced (Correct Answer)

Viruses Explanation: ***Virions containing genome X and nucleocapsid X will be produced*** - The virus containing **genome X** surrounded by **nucleocapsid Y** is a pseudotype. During the infection of a new cell, the **genome X** will direct the synthesis of new viral components, including **nucleocapsid X**. - Since the genetic material (genome X) dictates the production of viral proteins, the new virions will be genetically identical to virus X, thus containing its own genome and nucleocapsid. *Virions containing genome Y and nucleocapsid Y will be produced* - This is incorrect because the infecting particle carried **genome X**, not genome Y. - The genetic information encoded in the genome determines the type of progeny viruses produced. *No virions will be produced* - This is unlikely as the pseudotyped virus is capable of infection and delivery of a functional genome into the host cell. - The cell is presumed to be permissive for virus replication. *Virions containing genome X and nucleocapsid Y will be produced* - This would only happen if the **nucleocapsid Y** was somehow replicated independently of its original genome, which is not how viral replication works. - The progeny nucleocapsids are always encoded by the genome that is replicating within the cell. *Virions containing genome Y and nucleocapsid X will be produced* - This is incorrect. The infecting virus introduced **genome X** into the cell, not genome Y. - The genetic material delivered determines the type of viral particles that will be synthesized.

Viruses US Medical PG Question 9: A 30-year-old man is admitted to the hospital with a presumed pneumonia and started on antibiotics. Two days later, the patient shows no improvement. Blood cultures reveal yeast with pseudophyphae. Which of the following cell types is most likely deficient or dysfunctional in this patient?

• A. Eosinophils
• B. Macrophages
• C. Neutrophils (Correct Answer)
• D. T-cells
• E. B-cells

Viruses Explanation: ***Neutrophils*** - The presence of **yeast with pseudohyphae** in blood cultures, particularly *Candida*, indicates a fungal infection. - **Neutrophils** are crucial for the host defense against *Candida* and other fungal pathogens, so their deficiency or dysfunction would predispose to candidemia. - Neutropenia or neutrophil dysfunction (e.g., chronic granulomatous disease) significantly increases risk of invasive candidiasis. *Eosinophils* - **Eosinophils** are primarily involved in defense against **parasitic infections** and in allergic reactions. - They play a minimal role in the immune response to systemic fungal infections like candidemia. *Macrophages* - **Macrophages** are phagocytic cells that contribute to antifungal immunity, particularly in tissue surveillance and chronic infection control. - However, **neutrophils** are the primary and most critical defense against acute *Candida* bloodstream infections. - Macrophage deficiency alone does not typically predispose to candidemia as severely as neutrophil deficiency. *T-cells* - **T-cells** are important for cell-mediated immunity, particularly against **intracellular pathogens** and viral infections. - While they play a role in modulating antifungal responses, their deficiency typically leads to infections with *Pneumocystis jirovecii* or severe mucocutaneous candidiasis, rather than disseminated candidemia. *B-cells* - **B-cells** are responsible for **humoral immunity** through antibody production, which is primarily effective against extracellular bacteria and toxins. - They are not the primary line of defense against fungal infections such as candidemia.

Viruses US Medical PG Question 10: A 26-year-old woman comes to the physician because of several days of fever, abdominal cramps, and diarrhea. She drank water from a stream 1 week ago while she was hiking in the woods. Abdominal examination shows increased bowel sounds. Stool analysis for ova and parasites shows flagellated multinucleated trophozoites. Further evaluation shows the presence of antibodies directed against the pathogen. Secretion of these antibodies most likely requires binding of which of the following?

• A. CD28 to B7 protein
• B. CD80/86 to CTLA-4
• C. gp120 to CD4
• D. CD8 to MHC I
• E. CD40 to CD40 ligand (Correct Answer)

Viruses Explanation: ***CD40 to CD40 ligand*** - The interaction between **CD40 on B cells** and **CD40 ligand (CD40L) on activated T helper cells** is crucial for **T cell-dependent B cell activation** and antibody class switching. - This binding leads to the maturation of the immune response, including the secretion of **high-affinity antibodies** like IgA, which is especially important for mucosal immunity against pathogens like *Giardia lamblia* (the likely cause of the patient's symptoms). *CD28 to B7 protein* - The binding of **CD28 on T cells** to **B7 protein (CD80/86) on antigen-presenting cells (APCs)** provides the **second co-stimulatory signal** required for T cell activation. - While essential for T cell activation, this interaction primarily supports T cell proliferation and differentiation, rather than directly mediating antibody secretion by B cells. *CD80/86 to CTLA-4* - **CTLA-4 (cytotoxic T-lymphocyte-associated protein 4)** is a receptor on T cells that binds to **CD80/86 (B7)** on APCs with higher affinity than CD28. - This interaction provides an **inhibitory signal** that downregulates T cell activation, serving as a negative feedback mechanism, and does not promote antibody secretion. *gp120 to CD4* - The **gp120 glycoprotein** on the surface of **HIV** binds to the **CD4 receptor** on T helper cells, initiating the entry of the virus into the cell. - This interaction is specific to HIV infection and is not involved in the normal process of antibody secretion in response to other pathogens. *CD8 to MHC I* - **CD8** is a co-receptor expressed on **cytotoxic T lymphocytes (CTLs)** that binds to **MHC class I molecules** on target cells. - This interaction is essential for the recognition of virally infected or cancerous cells by CTLs, leading to their destruction, but it is not directly involved in antibody production.

Viruses Flashcard 1 of 10

Question: Which viral virulence factor promotes the release of progeny virions?_____

Answer: Neuraminidase

Viruses Flashcard 2 of 10

Question: What type of viruses are Flaviviruses? (DNA, RNA (sense), etc.)_____

Answer: Positive sense RNA

Viruses Flashcard 3 of 10

Question: RSV contains the virulence factor _____, which allows the production of multinucleated giant cells

Answer: F (fusion) protein

Viruses Flashcard 4 of 10

Question: _____ is a viral envelope protein that allows for mature virion release

Answer: Neuraminidase

Viruses Flashcard 5 of 10

Question: Filoviruses (ebola, marburg) may be transmitted via _____ or bats

Answer: primates (apes)

Extra Information:  Watch Ebolavirus, Marburgvirus (Filoviridae) [https://dashboard.sketchy.com/study/medical/courses/medical-microbiology/units/medical-microbiology-viruses/videos/medical-microbiology-viruses-rna-viruses-negative-sense-ebolavirus-marburgvirus-filoviridae?utm_source=anki&utm_medium=partnership&utm_campaign=february_update&utm_content=medical] https://onlinemeded.org/spa/infectious-disease?ref=anki 

Viruses Flashcard 6 of 10

Question: _____ Virus can result in pharyngitis with tonsillar exudates

Answer: Epstein-Barr

Extra Information:    https://onlinemeded.org/spa/infectious-disease?ref=anki 

Viruses Flashcard 7 of 10

Question: Which virus is associated with outbreaks on cruise ships? _____

Answer: Norovirus (norwalk virus)

Extra Information:  Watch Norovirus/Norwalk virus (Caliciviridae) [https://dashboard.sketchy.com/study/medical/courses/medical-microbiology/units/medical-microbiology-viruses/videos/medical-microbiology-viruses-rna-viruses-positive-sense-norovirusnorwalk-virus-caliciviridae?utm_source=anki&utm_medium=partnership&utm_campaign=february_update&utm_content=medical] https://onlinemeded.org/spa/infectious-disease?ref=anki 

Viruses Flashcard 8 of 10

Question: Which immunoglobulin is released into secretions (tears, saliva, mucus)? _____

Answer: IgA

Extra Information:  Watch associated Bootcamp video [https://app.bootcamp.com/med-school/immunology/videos/antibodies?index=6] https://onlinemeded.org/spa/immunology?ref=anki 

Viruses Flashcard 9 of 10

Question: Which DNA virus preferentially infects erythroid progenitors? _____

Answer: Parvovirus B19

Extra Information:    https://onlinemeded.org/spa/microbiology/dna-viruses/acquire?ref=anki 

Viruses Flashcard 10 of 10

Question: Enveloped viruses can have either an icosahedral or _____ shape (whereas naked viruses are all icosahedral)

Answer: helical

Extra Information:  https://onlinemeded.org/spa/infectious-disease?ref=anki