Virology Quiz on Hepatitis and Arboviruses

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Questions and Answers

What is the correct scientific term for a virus that relies on a coinfection in order to replicate?

Satellite (correct)

Co-dependent

Dependent

Parasite

What is the primary reason that hepatitis D (HDV) is more severe in patients who are coinfected with HBV?

The immune response to HDV is more aggressive in the presence of HBV, leading to more liver damage.

HDV replicates faster in the presence of HBV, causing a more rapid progression of the disease.

HDV directly damages the liver cells, leading to more severe symptoms. (correct)

HBV weakens the liver cells, making them more susceptible to HDV infection.

Which of the following is NOT a potential outcome of HDV infection in a patient who is a chronic carrier of HBV?

Chronic hepatitis

Liver failure

Fulminant hepatitis

Complete eradication of HBV infection (correct)

What is the primary way that Hepatitis E Virus (HEV) is transmitted?

Through the fecal-oral route (D) Signup and view all the answers

What distinguishes Arboviruses from other types of viruses?

They are able to multiply in both invertebrate and vertebrate hosts. (D) Signup and view all the answers

Which of the following is an example of a virus that can be transmitted through body fluids?

All of the above (D) Signup and view all the answers

Why is pegylated-interferon alpha considered an effective treatment for chronic hepatitis D?

It can reduce the effects of chronic hepatitis, but not eradicate the chronic carrier state. (D) Signup and view all the answers

Why is it important to be immunized against HBV in order to prevent HDV infection?

HDV cannot replicate without HBV, so being immunized against HBV prevents HDV infection. (B) Signup and view all the answers

In the United States, which of these animals are commonly known to be reservoirs for rabies? (Select all that apply)

Skunks (A), Raccoons (C), Bats (D) Signup and view all the answers

Which of these is NOT a characteristic of Ebola virus?

Is a single-stranded RNA virus with a bullet-shaped capsid (B) Signup and view all the answers

How are the clinical findings of rabies described?

Patients experience fever, anorexia, and tingling sensations at the bite site. (C) Signup and view all the answers

Which of the following is a direct cause of death in patients with Ebola hemorrhagic fever?

Excessive bleeding due to damage to blood vessels. (C) Signup and view all the answers

What is the main mode of transmission for Zika virus?

Through mosquito bites (B) Signup and view all the answers

Which of these is NOT a potential consequence of Zika virus infection during pregnancy?

Hemorrhagic shock (D) Signup and view all the answers

What is the primary mode of transmission of Ebola virus between humans?

Contact with infected blood, body fluids, or contaminated materials. (C) Signup and view all the answers

What is the primary clinical manifestation of rabies?

Encephalitis (C) Signup and view all the answers

What is the most effective strategy for preventing rabies after a suspected exposure?

Immediate administration of both rabies vaccine and immunoglobulins. (A) Signup and view all the answers

Which of the following is NOT a characteristic feature of Ebola virus?

Double-stranded RNA genome. (C) Signup and view all the answers

What is the most common cause of encephalitis and meningitis in the United States amongst all arboviruses?

West Nile Virus (C) Signup and view all the answers

What is the significance of the "shepherd's crook" appearance of some Ebola virions?

It is a morphological characteristic that may help in Ebola virus identification and classification. (A) Signup and view all the answers

How does rabies virus replicate and spread in the body?

It binds to acetylcholine receptors, replicates at the bite site, and travels to the CNS via sensory neurons (A) Signup and view all the answers

Which of the following pathogens can be transmitted through semen?

Zika virus (D) Signup and view all the answers

What is the main reason why the antibody response is ineffective in Ebola virus infection?

Viral proteins suppress the activity of lymphocytes, macrophages, and dendritic cells. (A) Signup and view all the answers

What is the primary reason why arboviruses commonly result in asymptomatic infections?

Humans are generally not the primary host for these viruses (C) Signup and view all the answers

Which of the following is a possible explanation for the high mortality rate associated with Ebola virus infection?

The virus causes widespread blood clotting and organ failure. (A) Signup and view all the answers

What is the correct term for the type of host that does not sustain ongoing transmission cycles for arboviruses?

Dead-end host (B) Signup and view all the answers

Which of the following is a direct-acting antiviral agent (DAA) that inhibits RNA polymerase in the Hepatitis C virus life cycle?

Sofosbuvir (D) Signup and view all the answers

What is the primary goal of treatment for chronic Hepatitis C?

Reduce the risk of liver-related health complications (D) Signup and view all the answers

Which of the following accurately describes the Hepatitis C virus?

An RNA virus that can lead to chronic infection in over 50% of cases (B) Signup and view all the answers

Which of the following medications is used to treat chronic Hepatitis B?

Tenofovir (C) Signup and view all the answers

Which of the following statements accurately describes the role of NS5A protein in Hepatitis C infection?

NS5A protein acts as a cofactor for RNA polymerase activity (A) Signup and view all the answers

Which of the following statements accurately describes the mechanism of hepatocyte damage caused by hepatitis viruses?

Hepatocyte death is primarily caused by the immune response, specifically cytotoxic T cells targeting viral antigens. (B) Signup and view all the answers

Hepatitis B Virus (HBV) differs from Hepatitis A Virus (HAV) in its mode of transmission. How is HBV primarily transmitted?

Via contaminated needles or blood transfusions (C) Signup and view all the answers

Which of the following clinical features is NOT commonly observed in patients infected with hepatitis viruses?

Diarrhea (B) Signup and view all the answers

What is the significance of covalently closed circular DNA (cccDNA) in the context of Hepatitis B Virus infection?

It serves as a reservoir for the virus, making it difficult to completely cure the infection. (B) Signup and view all the answers

What is 'seroconversion' in the context of Hepatitis B Virus infection?

The development of antibodies against the virus, indicating a transition from active infection to inactive carrier phase. (A) Signup and view all the answers

Which of the following antigens is considered an indicator of HBV transmissibility?

HBeAg (D) Signup and view all the answers

What is the primary reason for the elevated transaminase levels observed in patients with hepatitis infections?

The body's immune response to the infection causes liver cell damage, releasing transaminases. (D) Signup and view all the answers

What is the main difference between Hepatitis A and Hepatitis E?

Hepatitis A is more common in developed countries, while Hepatitis E is prevalent in developing countries. (C) Signup and view all the answers

Which of the following describes the action of maraviroc in the treatment of HIV?

Maraviroc binds to the CCR5 receptor on T cells, preventing HIV from entering the cell. (D) Signup and view all the answers

What is the primary target of the drug Saquinavir in HIV treatment?

The viral protease enzyme. (D) Signup and view all the answers

Which of the following statements accurately describes the mechanism of action of Emtricitabine in HIV treatment?

Emtricitabine is a nucleoside analog that competes with dCTP for incorporation into the elongating DNA chain, effectively halting chain elongation. (A) Signup and view all the answers

What is the primary function of gp120 and gp41 in the HIV virus?

They are essential for binding and entry of the virus into host cells. (A) Signup and view all the answers

Which of the following is NOT a characteristic of the HIV virus?

It is a DNA virus that replicates through transcription. (D) Signup and view all the answers

What is the primary target of Raltegravir in HIV treatment?

The viral integrase enzyme. (C) Signup and view all the answers

Which of the following accurately describes the role of Tenofovir in HIV treatment?

Tenofovir is a nucleoside analog that competes with dCTP for incorporation into the elongating DNA chain, effectively halting chain elongation. (D) Signup and view all the answers

What is the primary reason why HIV infects and kills helper CD4 T lymphocytes?

HIV specifically targets and destroys cells involved in the adaptive immune response, leading to immunosuppression and opportunistic infections. (D) Signup and view all the answers

What is the primary function of the protease enzyme in the HIV life cycle?

It cleaves viral polyproteins into functional proteins. (B) Signup and view all the answers

Which of the following is a key difference between the treatment of Ebola virus and HIV?

The treatment of Ebola virus infection involves a combination of monoclonal antibodies, while HIV infection is managed with a combination of antiretroviral drugs. (B) Signup and view all the answers

Study Notes

Hepatitis Viruses

Hepatitis viruses (A, B, C, D, E) primarily infect the liver.
All have surface proteins reacting with hepatocyte cell surface receptors.
They are non-cytotoxic; hepatocyte death results from cytotoxic T cells targeting viral antigens.
Clinical manifestations often include fever, anorexia, nausea, vomiting, jaundice, dark urine, pale feces, and elevated transaminase levels.
HAV is transmitted via fecal-oral route; HBV via blood, sexual contact, and during birth. HCV is transmitted via blood and sexual contact. HDV requires HBV coinfection; HEV transmitted via fecal-oral route.
Hepatitis A and E typically have no carriers; B and C can develop chronic carriers.
Relevant laboratory tests exist for diagnosing each, including IgM HAV, HBsAg, HBsAb, and IgM HBcAb for HBV. HCV tests and HDV tests (anti-delta Ag) are available.

Hepatitis A Virus (HAV)

Single-stranded RNA virus transmitted by fecal-oral route.
Humans are the only reservoir.
HAV infections typically resolve spontaneously in less than 8 weeks.
Incubation period 3-4 weeks. Most HAV infections are asymptomatic.
No predisposition to later liver cancer.
No antiviral therapy. Vaccination with inactivated HAV is available. Proper hygiene is crucial.

Hepatitis B Virus (HBV)

DNA virus, containing DNA polymerase.
Envelope contains surface antigen (HBsAg). HBeAg, another antigen, indicates viral transmissibility.
Chronic HBV infection persists >6 months, increasing cirrhosis, liver failure, or hepatocellular carcinoma risk.
~80% of acute infections are asymptomatic in the U.S.
~22,000 new cases in the U.S. in 2015 alone.
Treatment aims to reduce HBV DNA levels, and elevated alanine aminotransferase levels, for chronically infected patients. Seroconversion (inactive carrier phase) and achieving undetectable HBV DNA levels are treatment goals.
Antiviral therapies (entecavir, tenofovir) available. Vaccination available using surface antigen (HBsAg)

Hepatitis C Virus (HCV)

RNA virus.
~3.5 million people in the US have chronic HCV: >50% of acute infections become chronic.
Treatment (DAA) aims to achieve sustained virological response (SVR): undetectable HCV RNA 12 weeks after treatment.
SVR reduces liver-related health consequences (hepatocellular carcinoma, end-stage liver disease).
Several direct-acting antiviral (DAA) agents available (sofosbuvir, ombitasvir, glecaprevir).
No vaccine available.

Hepatitis D Virus (HDV)

Satellite virus that requires HBV co-infection to replicate.
Uses HBsAg as its envelope protein.
Single-stranded RNA genome, negative sense, covalently closed.
Encodes only one protein (delta antigen).
Chronic HDV infection is generally more severe in those coinfected with HBV.
Pegylated interferon alpha may reduce chronic hepatitis effects but not eliminate chronic carrier state. No antiviral therapy for HDV.

Hepatitis E Virus (HEV)

Single-stranded RNA virus transmitted via the fecal-oral route.
Common in developing countries. Similar to HAV but higher mortality rates in pregnant women (~30-100%).
Fulminant hepatitis, liver failure, can occur. Most cases resolve without negative outcomes
Treatment for immunocompetent patients relies on ribavirin; immunocompromised patients may require ribavirin. No vaccine available.

Arboviruses

Diverse group of viruses transmitted by arthropods (e.g., ticks, mosquitoes).
600 different arboviruses.
Named for the disease they cause or location of first isolation.
Typically multiply in both vector (bloodsucking arthropod) and vertebrate host.
Transmission via sufficient virus amount in the host's bloodstream.
Only female arthropods transmit viruses.
Incubation period= extrinsic incubation period= length of time for saliva to contain a sufficient amount of virus.
Humans are dead end hosts. Low viremia and brief viremia occurs in humans, meaning there is low infection risk.

West Nile Virus

Most common cause of arboviral encephalitis and meningitis in the U.S.
Primarily transmitted by mosquitoes.
Reservoir hosts are birds.
Usually mild infections (~80% are asymptomatic).
Some result in encephalitis and meningitis (~20% symptomatic).
No antiviral treatment. No vaccine.

Zika Virus

Transmitted by Aedes mosquitoes.
Vertebrate host = humans and non-human primates.
~80% of infections are asymptomatic.
Vertical transmission to fetuses can have profound fetal abnormalities (e.g., microcephaly) when infection occurs in the first trimester.
No antiviral therapy; supportive therapy.
No vaccine.
Safe sex practices, use of mosquito repellant, and environmental measures to control mosquito populations.

Rabies Virus

Enveloped virus with single-stranded RNA; bullet-shaped capsid, enclosed with lipoprotein.
Negative sense RNA genome.
Single serotype.
Anigenicity from envelope glycoprotein spikes.
Characterized by encephalitis.
Reservoir: many mammals (bats, skunks, raccoons).
Transmission: biting animal with rabies (virus enters saliva).
Symptoms begin, rabies almost always fatal.
No antiviral therapy; vaccination (and immunoglobulins) available for post-exposure prophylaxis.

Ebola Virus

Enveloped virus; longest viruses.
Single-stranded, non-segmented, negative sense RNA.
Contains RNA-dependent RNA polymerase.
Helical nucleocapsid.
5 strains (serotypes cross-react).
Natural reservoir: unknown (likely fruit bats, rodents).
Transmission: human-to-human via blood, body fluids, secretions.
Secondary Transmission: from contact with infected blood, secretions.
Needle/syringe re-use. May persist in survivor semen.
High mortality rate (~90%).
Symptoms include fever, headache, sore throat.
Treatments include combination therapy of monoclonal antibodies (atolivimab/maftivimab/odesivimab).
Vaccine available for Zaire ebolavirus. Proper handling of patient secretions important.

HIV (Human Immunodeficiency Virus)

Retrovirus (RNA virus which reverse transcribes its RNA genome).
Infects and kills helper CD4 T lymphocytes.
Causes loss of cell-mediated immunity, increasing opportunistic infections.
Other cells(displaying CD4 proteins on their surface) can also be infected.
Treatments for chronic HIV includes inhibiting entry, reversing transcription (emtricitabine), inhibiting maturation, inhibiting genome integration into host genome (Raltegravir), and other treatments that inhibit protease enzymes.
Prevention includes post-exposure prophylaxis (PEP) drugs to reduce risk of infection after potential exposure, Pre-exposure prophylaxis (PrEP) containing tenofovir or emtricitabine; circumscision can reduce infection risk.

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Description

Test your knowledge on various viruses, including hepatitis D, E, and rabies. This quiz covers coinfections, transmission methods, and clinical outcomes associated with these viruses. It’s a great way to deepen your understanding of virology and the impact of infectious diseases.