Histology Staining Techniques Quiz

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Questions and Answers

Which of the following statements accurately describes viremia?

It refers to local infections only.

It signifies a virus’s ability to spread systemically through the blood. (correct)

It is primarily associated with respiratory infections.

It indicates that a virus remains localized at the infection site.

Which route of virus entry is least likely to infect the central nervous system (CNS)?

Genital tract

Gastrointestinal tract (correct)

Abrasion

Respiratory tract

What is one consequence of alpha herpesviruses infecting pseudo-unipolar sensory neurons?

They cause widespread inflammation throughout the body.

They are primarily transmitted through contaminated water.

They reinfect the neurons only when the immune system is strong.

They can lead to CNS infections requiring specific transport mechanisms. (correct)

Which virus primarily spreads from muscles into somatic motor neurons?

Rabies virus (RABV) Signup and view all the answers

Which entry route might allow a virus to reach the brain directly?

Nasal olfactory epithelium Signup and view all the answers

How do poliovirus and rabies virus primarily reach the CNS?

By spreading through neuromuscular junctions Signup and view all the answers

Which virus classification typically involves infection through abrasions?

Enteroviruses Signup and view all the answers

What characteristic do viruses that cause generalized infection typically share?

They can undergo viremia. Signup and view all the answers

What type of cellular components does hematoxylin specifically stain?

Nuclear components including heterochromatin Signup and view all the answers

What are inclusion bodies typically associated with in infected cells?

Aggregates of stainable substances, usually proteins Signup and view all the answers

In which part of the brain are Negri bodies primarily found in rabies victims?

Ammon's horn of the hippocampus Signup and view all the answers

What characteristic coloration do Negri bodies exhibit, and why?

Eosinophilic due to the presence of ribonuclear proteins Signup and view all the answers

What type of viral infections particularly induce new surface antigens on infected cells?

Enveloped viral infections Signup and view all the answers

Which event is NOT typically involved in the pathogenesis of viral infections?

Induce inflammation as a primary response Signup and view all the answers

What immune mechanism must viruses overcome to ensure successful replication?

Interferon activity Signup and view all the answers

What does viremia refer to in the context of viral infections?

The spreading of viruses through the bloodstream Signup and view all the answers

What primarily allows the virus to spread to the central nervous system (CNS)?

Anterograde axonal transport along the olfactory nerve Signup and view all the answers

Which of the following accurately describes the composition of the blood-brain barrier (BBB)?

Microvascular endothelium cells with specialized tight junctions Signup and view all the answers

What is the primary direction of anterograde transport?

From the soma to the distal axon Signup and view all the answers

What type of viral infection is characterized by symptom-free periods followed by reactivation?

Chronic Viral Infection Signup and view all the answers

Which of the following is NOT a characteristic of a slow-fatal viral infection?

Rapid recovery from acute symptoms Signup and view all the answers

Which of the following viruses is associated with acute rapid death?

Ebola Signup and view all the answers

What is a risk factor associated with attenuated live vaccines?

They can genetically revert to pathogenic forms. Signup and view all the answers

What is the role of dyneins and kinesins in axonal transport?

They are microtubule-based motor proteins involved in transport. Signup and view all the answers

In terms of immune response, what distinguishes attenuated live vaccines from inactivated or sub-unit vaccines?

Attenuated live vaccines produce both humoral and cell-mediated immunity. Signup and view all the answers

What was demonstrated by the study on the recombinant modified vaccinia virus Ankara with the SARS spike glycoprotein?

It induces protective neutralizing antibodies targeting the receptor binding region. Signup and view all the answers

What type of viral infection typically has a long incubation period followed by a long illness?

Slow-Fatal Viral Infection Signup and view all the answers

Which of the following describes the mechanism for virus particles in the bloodstream to infect the brain?

Infecting brain microvascular endothelial cells (BMVECs) Signup and view all the answers

How many nucleotides differentiate the Sabin vaccine strain from the wild-type Leon strain of poliovirus?

10 nucleotides Signup and view all the answers

What was the frequency of paralytic disease caused by virulent revertant strains after the administration of the Sabin strain?

1 in 4 million Signup and view all the answers

What symptom characterizes oral herpes caused by the herpes simplex virus?

Infection of the lips, mouth, or gums Signup and view all the answers

What was concluded about the rDEN4delta30 dengue vaccine candidate in the study mentioned?

It is safe, immunogenic, and highly infectious. Signup and view all the answers

What does the abbreviation 'SARS' stand for in the context of vaccines?

Severe Acute Respiratory Syndrome Signup and view all the answers

Which type of vaccine typically produces a longer-lasting immune response?

Attenuated live vaccines Signup and view all the answers

What is the role of the E1 protein in viral replication?

It is responsible for the production of viral copies. Signup and view all the answers

Which types of HPV do the Gardasil vaccine target that are associated with cervical cancer?

Types 16 and 18 Signup and view all the answers

What is the benefit of using Gardasil besides preventing cervical cancer?

It prevents genital warts. Signup and view all the answers

What type of vaccine is used for chickenpox?

Live attenuated virus vaccine Signup and view all the answers

What is the significance of the structure of the virus in the context of vaccination?

It influences the infection affinity of the virus. Signup and view all the answers

What age group is GARDASIL 9 indicated for vaccination against HPV-related diseases?

9 to 26 years of age Signup and view all the answers

Which of the following statements about the E2 protein is true?

It interacts non-specifically with E1. Signup and view all the answers

What component of Gardasil helps it target multiple HPV types?

Inactivated L1 proteins Signup and view all the answers

Study Notes

Staining in Histology

Hematoxylin stains nuclear components such as heterochromatin and nucleoli.
Eosin stains cytoplasmic components, including collagen, elastic fibers, muscle fibers, and red blood cells.

Inclusion Bodies

Inclusion bodies are aggregates of stainable substances, mainly proteins within cells, often indicating viral replication.
Common viruses associated with inclusion bodies include Rabies Virus, Herpes Virus, and Measles Virus.
Negri bodies are eosinophilic inclusion bodies indicating rabies virus infection, primarily found in the cytoplasm of nerve cells.

Viral Interaction with Host Cells

Viruses induce new antigens on the surface of infected cells, especially enveloped viruses (e.g., herpes, orthomyxoviruses, retroviruses).
Infected cells become susceptible to cytotoxic T cells, detectable via immunofluorescence staining.

Viral Pathogenesis

Key events include invading the host, replicating in susceptible cells, evading immune defenses, and spreading through the bloodstream (viremia).
Respiratory aerosols from infected individuals contain viral particles, contributing to systemic transmission.

Infection Routes

Viruses can enter the host via various routes, including:
- Abrasion (e.g., cut)
- Inoculation (e.g., contaminated needle)
- Animal bites (e.g., rabies)
- Respiratory tract (e.g., influenza)
- Gastrointestinal tract (e.g., norovirus)
- Conjunctiva (e.g., HSV)
- Genital tract (e.g., HPV)

Nervous System Invasion

Alpha herpesviruses (e.g., HSV-1, VZV) infect sensory neurons, with rare CNS spread through anterograde axonal transport.
Rabies and poliovirus spread via neuromuscular junctions into the spinal cord.
Various viruses can traverse the blood-brain barrier (BBB) via infected leukocytes or BMVECs.

Types of Viral Infections

Acute infections lead to rapid recovery or death (e.g., influenza, rabies).
Chronic infections exhibit symptom-free periods with potential reactivation (e.g., herpes).
Slow-fatal infections, such as HIV, manifest as long incubation periods followed by illness.

Vaccine Development

Gardasil vaccine targets HPV types 16, 18, 6, and 11, preventing cervical cancer and genital warts.
Chickenpox vaccine uses a live attenuated virus to provide immunity against varicella-zoster virus.
Ongoing research includes developing vaccines against HIV and dengue through various innovative approaches.

Live Attenuated vs Inactivated Vaccines

Live attenuated vaccines typically provide longer-lasting immunity, generating both humoral and cell-mediated responses.
Inactivated or sub-unit vaccines primarily stimulate humoral immunity.
Concerns exist regarding the genetic reversion potential of live attenuated vaccines, such as the polio vaccine.

Genetic Variability in Vaccines

Genetic differences between attenuated (e.g., Sabin polio) and wild-type strains can be minimal but significant for pathogenicity.
Cases of virulent revertant strains highlight the need for careful monitoring of vaccine-derived strains.

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Description

Test your knowledge on the staining techniques of hematoxylin and eosin used in histology. This quiz will cover the specific components these stains target, including nuclear and cytoplasmic elements. Understand the significance of inclusion bodies in the context of viral multiplication.