Viral Infections & Pathogenesis
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Questions and Answers

What is the term used to describe the increase in antibody titer to a virus?

  • Viral growth
  • Seroconversion (correct)
  • Nucleic acid detection
  • Cytopathic effect

Which method is used to identify viruses based on their size and morphology?

  • Cell culture
  • Immunodiagnostics
  • Antibody titering
  • Electron microscopy (correct)

What does IgM in a patient's blood indicate?

  • Past infection
  • Recent vaccination
  • Chronic infection
  • Acute infection (correct)

What is required for the growth of viruses?

<p>Living cells (A)</p> Signup and view all the answers

How can viral nucleic acids be detected in a patient's sample?

<p>With cDNA or cRNA probes (A)</p> Signup and view all the answers

What does a 4-fold increased concentration of IgG indicate?

<p>Acute infection (C)</p> Signup and view all the answers

Which method is used to amplify viral nucleic acids when only small amounts are present?

<p>Polymerase chain reaction (PCR) (D)</p> Signup and view all the answers

How are viral antigens typically detected in a patient?

<p>By testing blood or body fluids (A)</p> Signup and view all the answers

What is the primary purpose of a vaccine?

<p>To stimulate the production of antibodies (D)</p> Signup and view all the answers

Antiviral therapies target specific steps in the virus lifecycle. Which of the following is NOT a targeted step?

<p>Antibody production (C)</p> Signup and view all the answers

What are the primary components used for the classification of viruses?

<p>Nucleic acid, capsid, and envelope (A)</p> Signup and view all the answers

Which of the following statements is true about positive-sense RNA viruses?

<p>They have RNA that can be directly translated into proteins. (B)</p> Signup and view all the answers

What is one of the five main effects of virus infection on a cell?

<p>Fusion of cells to form multinucleated cells (B)</p> Signup and view all the answers

What is the significance of inclusion bodies in infected cells?

<p>They are indicative of viral replication and contain viral proteins or particles. (D)</p> Signup and view all the answers

Most DNA viruses are characterized by their structure. Which of the following is correct?

<p>They are mostly double-stranded, icosahedral, and replicate in the nucleus. (A)</p> Signup and view all the answers

What effect does cell lysis have on virus-infected cells?

<p>It typically leads to the release of viral particles. (A)</p> Signup and view all the answers

Which group commonly refers to HHAPPPy viruses?

<p>A group of specific DNA viruses known for particular characteristics (B)</p> Signup and view all the answers

What is the primary reason for using cell cultures in virus identification?

<p>Viruses can only replicate in living cells. (D)</p> Signup and view all the answers

Which microscopic technique is specifically noted for revealing characteristic inclusions or giant cells?

<p>Light microscopy (B)</p> Signup and view all the answers

How do negative-sense RNA viruses operate before protein production can begin?

<p>They need to be transcribed into complementary positive-sense RNA. (A)</p> Signup and view all the answers

What cytopathic effect (CPE) is typically associated with virus growth in cell cultures?

<p>Characteristic inclusion bodies (A)</p> Signup and view all the answers

Which microscopy technique uses fluorescent antibody staining for virus identification?

<p>UV microscopy (C)</p> Signup and view all the answers

What is the main function of electron microscopy in virus detection?

<p>To characterize virus particles by size and morphology (A)</p> Signup and view all the answers

What is typically examined in clinical specimens for virus identification?

<p>Biopsy material or skin lesions (D)</p> Signup and view all the answers

What characteristic findings can suggest a presumptive viral identification in cell cultures?

<p>Cytopathic effects and inclusion bodies (A)</p> Signup and view all the answers

Which of the following does NOT represent a direct method of identifying viruses?

<p>Antigen-antibody testing (B)</p> Signup and view all the answers

What is the correct order of the clinical stages of a typical viral infection?

<p>Incubation period, Prodromal period, Specific-illness period, Recovery period (A)</p> Signup and view all the answers

Which of the following is NOT a category of host defenses against viruses?

<p>Inflammatory immune response (D)</p> Signup and view all the answers

Which types of immunity are included in the specific (adaptive) immune response?

<p>Humoral and cell-mediated immunity (B)</p> Signup and view all the answers

What are virokines primarily secreted by?

<p>Infected host cells (D)</p> Signup and view all the answers

What is the primary function of interferons in the immune response?

<p>They serve as an early defense against viruses (A)</p> Signup and view all the answers

Which of the following best describes the function of cytokine decoys?

<p>They bind and neutralize immune mediators. (A)</p> Signup and view all the answers

Which of the following techniques can be used for the microscopic identification of viruses?

<p>Light microscopy (D)</p> Signup and view all the answers

What is one of the mechanisms by which viruses maintain their presence in the host cell?

<p>Maintaining viral latency. (A)</p> Signup and view all the answers

What is the most common method for processing viral specimens?

<p>Class II biological safety cabinet (C)</p> Signup and view all the answers

Which approach is NOT included in the five techniques for diagnosing viral diseases?

<p>Bacterial culture (A)</p> Signup and view all the answers

What does antigenic variation allow viruses to do?

<p>Escape recognition by the immune system. (C)</p> Signup and view all the answers

What characteristic is particularly noted when performing microscopic identification of viruses?

<p>Presence of characteristic inclusion bodies (C)</p> Signup and view all the answers

How do virulent strains of viruses differ from non-virulent strains?

<p>They have a greater ability to cause disease. (D)</p> Signup and view all the answers

What type of proteins do some viruses encode that can manipulate the immune response?

<p>Immunomodulatory proteins (D)</p> Signup and view all the answers

Which immune mediators can cytokine decoys specifically neutralize?

<p>Interleukin-1 and tumor necrosis factor (C)</p> Signup and view all the answers

What do virokines compete with in the host?

<p>Normal host signals for their target receptors (B)</p> Signup and view all the answers

Flashcards

Viral Pathogenesis (Cellular Level)

A virus's ability to cause disease on a cellular level, affecting individual cells.

Viral Pathogenesis (Patient Level)

A virus's ability to cause disease on a patient level, encompassing the entire infected organism.

Viral Nucleic Acid

The genetic material of a virus, which can be either DNA or RNA.

Viral Capsid

The protein coat that surrounds the viral nucleic acid, providing structural support and protection.

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Viral Envelope

An outer membrane surrounding the capsid, which often contains viral proteins that aid in attachment and entry into host cells.

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Negative-sense RNA Transcription

The process of a negative-sense RNA virus converting its RNA into a positive-sense RNA strand, which can then be translated into proteins.

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Latent Infection

A viral infection where the virus remains dormant within the host cell, often without causing symptoms.

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Inclusion Bodies

Discrete areas within an infected cell that contain viral proteins or viral particles.

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Virokines

A type of protein secreted by infected cells that resembles cytokines, growth factors, or complement regulators. They compete with normal host signals by binding to their target receptors, altering the host's response to the infection.

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Virulence

The ability of a virus to cause disease. Some viruses have specific genes that contribute to this ability.

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Antigenic Variation

The ability of a virus to change its surface proteins, making it harder for the immune system to recognize and attack.

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Viral Latency

A virus's ability to remain dormant within a host cell for extended durations, avoiding detection by the immune system.

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Malignant Transformation

The process by which a virus alters the normal growth and behavior of a cell, potentially leading to cancer.

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Cytokine Decoys

Proteins released by virus-infected cells that bind and neutralize immune mediators like interleukin-1 (IL-1) and tumor necrosis factor (TNF). This prevents the immune system from activating cells that fight the infection.

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Immunomodulatory Proteins

Proteins that directly target and destroy immune mediators, thereby weakening the host's immune response.

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Cytopathic Effect

A virus's ability to induce cell death, causing damage to the infected organism.

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Incubation period

The period in which viruses multiply within the host, but no symptoms are present.

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Prodromal period

The early stage of a viral infection characterized by mild, general symptoms, such as fatigue, headache, and nausea.

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Specific-illness period

The stage of a viral infection when specific symptoms associated with the particular virus appear.

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Recovery period

The stage of a viral infection where the body recovers from the illness.

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Nonspecific immune response

A type of immune response that is present from birth and does not require prior exposure to a pathogen. It is a general defense against a wide range of invaders.

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Specific immune response

A type of immune response that is acquired after exposure to a specific pathogen, providing targeted protection against that pathogen.

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Interferon

A soluble protein produced by cells in response to viral infection, interfering with viral multiplication.

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Natural killer cells

A type of white blood cell that attacks and kills cells infected with viruses without the need for prior sensitization.

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Microscopic Identification of Viruses

A method for detecting viruses by observing unique structures formed within infected cells.

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Virus Growth in Cell Culture

Viruses can only replicate in living cells, so they are grown in cell cultures to study their growth and effects.

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Cytopathic Effect (CPE)

The unique changes that occur in cells infected by a virus, often visible under a microscope.

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UV Microscopy

A type of microscopy that uses fluorescent antibodies to identify viruses in infected cells.

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Multinucleated Giant Cells

Giant cells with multiple nuclei, a common sign of viral infection.

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Electron Microscopy

Microscopy that uses electrons to visualize the structure of tiny viruses.

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Virus Morphology

The shape and size of a virus, which can help identify it.

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Seroconversion

A change in a patient's serum from not having antibodies against a specific virus to having antibodies against that virus. This indicates a recent infection.

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Direct Microscopic Examination

The process of using light microscopy to directly observe viruses within infected cells. This method can be used to detect and identify viruses in clinical specimens like biopsies.

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Viral Nucleic Acid Detection

Detection of specific viral DNA or RNA in patient samples, indicating current infection. This method uses probes that bind to complementary viral sequences.

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PCR (Polymerase Chain Reaction)

A diagnostic test used to detect the presence of a virus by amplifying its genetic material, even in small amounts.

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Vaccine

A substance that stimulates the immune system to produce antibodies against a specific disease.

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Antiviral Therapy

The process of treating a viral infection using drugs that target specific viral processes, such as replication or assembly.

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Acute Infection

An immune response to a virus that appears within a short time after infection and involves a rapid increase in the concentration of IgG antibodies.

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Chronic Infection

An immune response to a virus that persists over a long period, characterized by sustained levels of IgG antibodies.

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Study Notes

Viral Infections & Pathogenesis

  • Viral infections are classified based on chemical and morphological criteria.
  • Major components used in viral classification include the nucleic acid (type and structure; DNA vs. RNA), capsid (icosahedral vs. helical), and envelope (naked vs. enveloped).

Viral Pathogenesis

  • Viral disease can be studied at two levels: changes within individual cells and processes in the infected patient.
  • Classifications of DNA and RNA viruses exist as well as their common diseases.

Viral Family Classification

  • Some DNA viruses are double-stranded and show icosahedral symmetry, replicating in the nucleus.
  • Some DNA viruses, like Parvovirus, are single-stranded DNA that replicate in the cytoplasm, not icosahedrally.
  • Most RNA viruses are single-stranded (+ vs. -) sense, enveloped, and replicate in the cytoplasm.
  • Positive-sense RNA (+RNA) viruses can be directly translated into proteins.
  • Negative-sense RNA (-RNA) viruses must first be transcribed into complementary positive-sense RNA before protein production can begin.

Infected Cell Effects

  • Viral infection can result in cell death (lysis), cell fusion (multinucleated giant cells), malignant transformation, no noticeable change, or persistence (latent infections).
  • Inclusion bodies are discrete areas within infected cells containing viral proteins or particles.

Malignant Transformation

  • Viral infection can cause certain viruses to exhibit unrestrained growth, prolonged survival, and morphologic changes, leading to malignant transformation of infected cells.
  • Oncoviruses carry oncogenes in their genetic material that can be integrated into host cell genomes, activating oncoproteins and driving malignant transformation. HPV and EBV are examples.
  • Rapid viral replication and immune destruction can drive accelerated cell division, leading to increased mutagenesis and potentially cancerous changes. HCV and HIV are examples.

Viral Pathogenesis in the Infected Patient

  • Viral pathogenesis in humans involves virus transmission, entry, replication and damage to cells, spread to other cells and organs, the immune response, and potential persistence.
  • Understanding portals of entry and possible diseases associated with specific viruses is important.

Viral Virulence

  • Viral strains vary significantly in their ability to cause disease.
  • Some viruses have genes encoding molecules inducing cytopathic effects, promoting malignant transformation, exhibiting antigenic variations, allowing viral latency.
  • Viruses may evade the host immune response by using cytokine decoys, virokines, and immunomodulatory proteins.

Multiple Antigenic Types (Serotypes)

  • Some viruses, such as rhinoviruses and influenza, have multiple serotypes (antigenic types).
  • Having multiple serotypes enhances the virus' ability to cause infection across the population because previous exposure to one serotype does not grant immunity to others.

Persistent Viral Infections

  • In some cases, viruses remain in the body after the host recovers, resulting in persistent infections.
  • Viral latency can occur through various mechanisms, including the action of latency genes, location of the virus in immunologically sheltered sites, and rapid antigenic variation.

Types of Persistent Viral Infections

  • Chronic-carrier infections: These viruses replicate continuously and are constantly shed, serving as a source of infection to others. Chronic hepatitis B and C are one example.
  • Latent infections: Virus replication may stop after initial infection, but in some cases, symptoms may reappear, accompanied with virus production.
  • Slow virus infections: A prolonged period between infection and disease onset.

Laboratory Techniques (Diagnosis)

  • Viral specimens are typically processed in class II biological safety cabinets.
  • Diagnosis involves identification of the virus in cell culture, microscopic examination (light or electron microscopy), serologic procedures to detect antibody titers or IgM, or detection of viral antigens or nucleic acids.

Viral Vaccination

  • Vaccines are preparations designed to produce immunity against diseases by inducing antibody production.
  • Live attenuated and inactivated vaccines are common methods of viral vaccination. They can differ in how long immunity lasts, their efficacy, ease of use, and potential for reversion to virulence.

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Related Documents

Viral Infections & Pathogenesis PDF

Description

This quiz covers the classification and pathogenesis of viral infections, focusing on the criteria used in categorizing viruses based on their nucleic acid, capsid, and envelope. It also delves into the mechanisms of viral disease at cellular and patient levels. Perfect for students studying virology.

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