Virology Diagnostic Techniques

Podcast

Play an AI-generated podcast conversation about this lesson

Questions and Answers

Which technique provides the MOST detailed information about the atomic structure of a virus?

X-ray crystallography (correct)
Negative staining electron microscopy
Cryo-electron microscopy
Inverted light microscopy of infected cells

What is the primary purpose of using potassium phosphotungstate or ammonium molybdate in negative staining electron microscopy?

To increase the conductivity of the sample
To specifically stain viral proteins for identification
To enhance the penetration of the electron beam through the sample
To stain the background, creating contrast with the virus particle (correct)

Syncytia formation, a cytopathic effect (CPE) observed in virus-infected cells, involves what process?

Rapid cell division leading to tumor formation.
Fragmentation of the nucleus.
Compaction of the cytoplasm.
Fusion of multiple cells into a single, multinucleated cell. (correct)

Which method is LEAST likely to be used in a typical diagnostic virology lab for rapid virus identification?

Cryo-electron microscopy of viral structures (C) Signup and view all the answers

In viral diagnostics, what does the observation of cytopathic effects (CPE) under an inverted light microscope primarily indicate?

The virus infection is causing damage or abnormalities to the cells. (C) Signup and view all the answers

What is a major limitation of using electron microscopy directly on clinical samples for virus detection?

Low viral load in samples may make detection difficult without prior amplification. (D) Signup and view all the answers

Which of the following cell lines is LEAST likely to be used for culturing a wide range of respiratory viruses for diagnostic purposes?

Vero cells (D) Signup and view all the answers

Consider a scenario where a novel virus is suspected. Which approach would be the MOST effective FIRST step in characterizing its structure, assuming limited resources and equipment?

Negative stain electron microscopy to estimate size and shape (A) Signup and view all the answers

Which method is LEAST effective for quantifying viral load in a sample with low viral titer and high levels of background nucleic acids?

Standard PCR followed by gel electrophoresis and visual inspection. (D) Signup and view all the answers

A researcher aims to study the pathogenesis of a novel respiratory virus in vivo. Which animal model would be the MOST suitable for accurately mimicking the human immune response and disease progression?

Non-human primates due to their close phylogenetic relationship to humans. (B) Signup and view all the answers

In a plaque assay, what cellular process is MOST directly responsible for the formation of visible plaques?

The localized death of cells due to viral infection and lysis. (A) Signup and view all the answers

Following plaque purification, a researcher observes significant variation in the growth rate of the isolated virus in different cell lines. What is the MOST likely explanation for this observation?

The virus has undergone genetic drift, resulting in subpopulations with varying tropism. (B) Signup and view all the answers

A novel virus exhibits poor replication in standard cell culture. Which strategy is LEAST likely to enhance viral replication for downstream applications?

Treatment of cells with broad-spectrum antibiotics to eliminate potential bacterial contamination. (B) Signup and view all the answers

During vaccine production using embryonated eggs, a high rate of genetic mutations is observed in the produced virus. What modification to the production process would MOST effectively minimize these mutations?

Reducing the number of passages in embryonated eggs to minimize adaptive evolution. (A) Signup and view all the answers

Which approach would be the LEAST effective for detecting a novel virus with an unknown genome sequence in a clinical sample?

Southern blot using a probe against a common viral gene, such as reverse transcriptase. (C) Signup and view all the answers

A researcher aims to quantify the expression of a specific viral mRNA transcript in infected cells. Which of the following methods is MOST appropriate for this purpose?

Northern blotting. (D) Signup and view all the answers

In the context of viral diagnostics, what is the primary advantage of using reverse transcriptase PCR (RT-PCR) over standard PCR?

RT-PCR enables the detection and quantification of viruses with RNA genomes, which standard PCR cannot directly amplify. (C) Signup and view all the answers

During gel electrophoresis, what key factor determines the migration rate of amplified viral genes through the agarose gel?

The size of the DNA fragments, with smaller fragments migrating faster. (C) Signup and view all the answers

What is the crucial role of oligonucleotide primers in the Polymerase Chain Reaction (PCR) for amplifying viral DNA?

They provide a starting point for DNA polymerase to initiate DNA synthesis, targeting specific regions of the viral genome. (C) Signup and view all the answers

What is the significance of comparing amplified viral gene sizes to molecular weight markers after gel electrophoresis?

To verify the identity of the amplified viral gene based on its expected size. (C) Signup and view all the answers

In the context of real-time PCR, what distinguishes absolute quantification from relative quantification when assessing viral load?

Absolute quantification involves comparing the viral gene copy number to a standard curve, whereas relative quantification compares the viral gene expression to a reference gene. (C) Signup and view all the answers

What is the role of reverse transcriptase in the context of RT-PCR?

To synthesize a DNA copy (cDNA) from an RNA template. (D) Signup and view all the answers

Consider a scenario where a new viral strain is discovered. How would the design of PCR primers need to be adjusted to ensure accurate amplification of the new viral genome?

The primer sequences must be designed to be complementary to conserved regions unique to the new viral strain's genome. (C) Signup and view all the answers

Ethidium bromide and Gel Red are used to stain DNA in agarose gels. Although both bind to DNA, what is a key difference that has led to the increasing use of Gel Red?

Gel Red is proven to be non-mutagenic, unlike ethidium bromide which is a known mutagen. (D) Signup and view all the answers

Flashcards

Confocal (Fluorescent) Light Microscopy

Uses fluorescently tagged antibodies to detect virus antigens within infected cells (nucleus, cytoplasm, or membrane).

Virus Infection Models

Laboratory animals, especially mice and non-human primates, used to model viral infections and study disease progression.

Embryonated Eggs

A method used to cultivate viruses for vaccine production, especially for influenza, herpes, and varicella-zoster viruses.

Plaques (in Plaque Assay)

Areas where cells have been infected and killed by viruses, appearing as clear zones in a cell monolayer culture.