Rabies Virus Overview

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Questions and Answers

Which of the following characteristics distinguishes rabies virus?

  • It is a naked DNA virus.
  • It is a naked RNA virus.
  • It is a non-enveloped DNA virus.
  • It is an enveloped RNA virus. (correct)

Rabies virus is transmitted through direct contact with saliva from an infected animal.

True (A)

What is the scientific name of the family to which rabies virus belongs?

Rhabdoviridae

Rabies is a ______ disease, meaning it can be transmitted from animals to humans.

<p>zoonotic</p> Signup and view all the answers

Match the following aspects of rabies virus with their corresponding descriptions:

<p>Structure = Bullet-shaped, enveloped virus with a helical nucleocapsid Replication = Entry into host cells, transcription, translation, replication, assembly, budding, and spreading Diagnosis = Laboratory techniques, clinical signs and symptoms Prevention = Vaccination, Post-Exposure Prophylaxis (PEP)</p> Signup and view all the answers

Which of the following is NOT a method commonly used for rabies virus diagnosis?

<p>Blood culture (C)</p> Signup and view all the answers

Rabies virus can be cultivated in cell cultures.

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

What does PEP stand for in the context of rabies prevention?

<p>Post-Exposure Prophylaxis</p> Signup and view all the answers

What is the primary method for preventing rabies transmission in both animals and humans?

<p>Widespread vaccination (D)</p> Signup and view all the answers

What are the primary hosts for rabies virus infections?

<p>Dogs and other mammals (C)</p> Signup and view all the answers

Once rabies symptoms develop, there is a highly effective cure available.

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

What are the two primary components of post-exposure prophylaxis (PEP) for rabies?

<p>Wound care and vaccinations (RIG and rabies vaccine)</p> Signup and view all the answers

The rabies virus can survive for extended periods outside of a living host.

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

What is the key role of the rabies virus' glycoprotein?

<p>The rabies virus glycoprotein is responsible for attaching to and entering host cells, initiating infection. This process is crucial for the virus to spread within the body.</p> Signup and view all the answers

The rabies virus, a member of the ______ family, is known for its neurotropic nature.

<p>Rhabdoviridae</p> Signup and view all the answers

Match the following terms related to rabies with their descriptions:

<p>Rabies Immunoglobulin (RIG) = A series of vaccinations administered over 14 days Rabies Vaccine = Infiltrated around the wound and administered intramuscularly Wound Care = Thorough cleaning and washing of the wound with soap and water</p> Signup and view all the answers

The [BLANK] protein of the rabies virus is crucial for the assembly and budding process of new viral particles.

<p>matrix</p> Signup and view all the answers

Match the following cell types with their roles in rabies virus infection.

<p>Vero cells = African green monkey kidney cells used for studying rabies virus in laboratory settings Neurons = Primary targets of rabies virus in the central nervous system Immune cells = Can respond to rabies virus infection, but the virus often evades the immune response Muscle cells = Rarely infected by rabies virus, but the virus can travel to muscle cells through nerves</p> Signup and view all the answers

What is the primary method of preventing rabies in humans?

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

Which of the following environmental factors can inactivate the rabies virus?

<p>All of the above (E)</p> Signup and view all the answers

Once clinical symptoms of rabies appear, the disease is nearly always fatal.

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

The rabies virus is highly stable outside the host and can withstand harsh environmental conditions.

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

What is the most common mode of rabies transmission?

<p>Animal bites</p> Signup and view all the answers

Describe the role of the World Health Organisation (WHO) in combating rabies.

<p>The WHO plays a crucial role in educating about rabies, promoting vaccination programs, and providing guidance for rabies control strategies.</p> Signup and view all the answers

The rabies virus exhibits a unique pathogenicity known as ______, which means it targets the nervous system.

<p>neurotropism</p> Signup and view all the answers

Match the following viral proteins with their primary function:

<p>Glycoprotein (G) = Attachment to host cell receptors Large protein (L) = RNA-dependent RNA polymerase Nucleocapsid protein (N) = Protects the viral RNA genome</p> Signup and view all the answers

Which of the following is NOT a mode of rabies transmission?

<p>Direct transmission through the air (E)</p> Signup and view all the answers

The glycoprotein (G) is a major target for the immune system and is a key component of rabies vaccines.

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

What is the role of the Large protein (L) in the rabies virus?

<p>The Large protein (L) is responsible for both transcription (creating mRNA from the viral RNA genome) and replication (creating new copies of the viral RNA genome).</p> Signup and view all the answers

Rabies virus exhibits a strong affinity for neurons, infecting and destroying them.

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

Which of the following is NOT a method for cultivating rabies virus?

<p>Bacteriological Culture (A)</p> Signup and view all the answers

The time between infection and the onset of rabies symptoms is called the ______ period.

<p>incubation</p> Signup and view all the answers

What is the primary receptor on host cells that rabies virus attaches to?

<p>Glycoprotein (G) spikes</p> Signup and view all the answers

Match the following viral proteins involved in rabies replication with their corresponding functions:

<p>Nucleoprotein (N) = Forms the nucleocapsid that protects the viral RNA genome. Phosphoprotein (P) = Assists the polymerase in transcription and replication. Matrix protein (M) = Forms the inner layer of the viral envelope. Glycoprotein (G) = Attaches to host cell receptors, mediating entry. Polymerase (L) = Transcribes the viral RNA genome and synthesizes new RNA strands.</p> Signup and view all the answers

How does rabies virus enter the host cell?

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

The rabies virus can evade the host immune response, which contributes to its ability to spread within the nervous system.

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

What are two key steps in the replication of rabies virus after it enters a host cell?

<p>Transcription and Translation</p> Signup and view all the answers

Which of the following viruses is NOT part of the Lyssavirus genus?

<p>Ebola virus (D)</p> Signup and view all the answers

Lyssaviruses are known for their ability to infect a wide range of animals, but they cannot infect humans.

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

What is the primary characteristic that gives lyssaviruses their name and describes their main target in the body?

<p>Neurotropism</p> Signup and view all the answers

The rabies virus has a distinctive ______ shape.

<p>bullet</p> Signup and view all the answers

Match the following rabies virus proteins with their respective functions:

<p>Nucleoprotein (N) = Encapsulates the viral RNA genome and forms the nucleocapsid Phosphoprotein (P) = Acts as a cofactor for the viral polymerase, essential for RNA replication and transcription Matrix protein (M) = Located between the nucleocapsid and the envelope, involved in virus assembly and budding Glycoprotein (G) = Forms the surface spikes of the virus, responsible for attachment to and entry into host cells</p> Signup and view all the answers

Which of the following is NOT a distinguishable characteristic of the rabies virus?

<p>Double-stranded RNA genome (A)</p> Signup and view all the answers

The rabies virus is surrounded by an envelope that is derived from the host cell membrane.

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

What is the approximate size of the rabies virus genome in nucleotides?

<p>12,000</p> Signup and view all the answers

Flashcards

Rabies Virus Infection Process

Attachment to host cell receptors initiates rabies infection.

Viral RNA-dependent RNA Polymerase

Enzyme responsible for viral RNA transcription and replication.

Rabies Virus Stability

Rabies virus is fragile outside the host, sensitive to environment.

Heat Sensitivity

Elevated temperatures can rapidly inactivate the rabies virus.

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Drying Effect

Desiccation is detrimental; virus does not survive in dry conditions.

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Modes of Transmission

Rabies mainly spreads through bites and scratches from infected animals.

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Neurotropism

Rabies virus has a strong tendency to affect nervous tissue.

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Environmental Inactivation

Rabies virus can be inactivated by disinfectants and extreme pH levels.

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Widespread Vaccination

Vaccinating dogs reduces rabies cases in animals and humans.

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Vaccination of Domestic Animals

Cats and livestock should be vaccinated per local guidelines.

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Post-Exposure Prophylaxis (PEP)

Treatment after exposure to rabies includes wound care and vaccination.

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Wound Care

Thoroughly clean and wash the wound with soap and water.

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Rabies Immunoglobulin (RIG)

Injected around the wound to provide immediate protection.

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Public Health Education

Raising awareness about rabies prevention and vaccination importance.

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No Cure for Established Infection

Once rabies symptoms appear, there is no effective treatment.

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Neurological Damage

Rabies virus targets neurons, causing severe neurological symptoms.

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Rabies Virus

A deadly virus affecting the central nervous system, transmitted through animal bites.

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First Rabies Vaccination

The first successful vaccination against rabies was developed by Louis Pasteur in 1885.

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Rhabdoviruses

A family of viruses known for their bullet-shaped particles, which includes the rabies virus.

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Rabies Virus Glycoprotein

A surface protein that enables the rabies virus to enter host cells and triggers immune responses.

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Rabies Diagnosis

Diagnosis of rabies is primarily through clinical symptoms and can be confirmed by lab tests.

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Human Rabies Immunoglobulin (HRIG)

A treatment option for rabies exposure, providing immediate passive immunity against the virus.

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Immune Escape Strategy

Methods employed by the rabies virus to evade the host's immune system for survival.

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Rabies Virus Life Cycle

The process by which the rabies virus infects a host, replicates, and spreads.

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Rabies virus transmission

The rabies virus travels along peripheral nerves to the CNS after entry through a bite wound.

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Long incubation period

The time from rabies infection to symptom onset can vary from days to years, complicating diagnosis.

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Progressive neurological disease

Rabies causes a fatal neurological disease after reaching the CNS, leading to severe symptoms.

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Immune evasion

Rabies virus has evolved to avoid detection and attack by the host’s immune system, allowing its spread.

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Vero cells

Cell culture method using monkey kidney cells to grow rabies virus for research.

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Animal models for cultivation

Historical method of growing rabies virus in lab animals like mice and hamsters, now less common.

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Viral replication steps

Involves attachment, uncoating, transcription, translation, and genome replication within host cells.

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mRNA translation

The process where mRNA from rabies virus is translated into five essential viral proteins by host ribosomes.

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Zoonotic potential

The ability of lyssaviruses to infect both animals and humans.

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Rabies lyssavirus

The specific species responsible for most rabies cases in humans worldwide.

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Bullet-shaped virion

A distinguishable feature of the rabies virus, resembling a bullet.

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Negative-sense RNA

A type of viral RNA that is complementary to mRNA, necessary for protein production.

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Glycoprotein spikes

Surface structures on the rabies virus important for entering host cells.

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Nucleoprotein (N)

Protein that encapsulates the viral RNA genome and forms the nucleocapsid.

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Matrix protein (M)

Protein located between the nucleocapsid and envelope, crucial for virus assembly.

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Lyssavirus

Genus that includes the rabies virus.

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Vaccine-preventable

Diseases that can be prevented through vaccination.

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Zoonotic disease

A disease transmitted from animals to humans.

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Central Nervous System (CNS)

The part of the nervous system consisting of the brain and spinal cord.

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Symptoms of rabies

Clinical signs such as fever, confusion, and paralysis.

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Diagnosis Techniques

Methods used to identify rabies, including lab tests.

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Study Notes

Rabies Virus (Rhabdovirus)

  • Rabies is a zoonotic, vaccine-preventable viral disease affecting the central nervous system.
  • Transmission is commonly through animal bites (typically by dogs).
  • The virus infects mammals, including dogs, cats, livestock, and wildlife.
  • Rabies is nearly always fatal once clinical symptoms appear.
  • Symptoms appear in varying timescales (from a few days to several years).

Classification

  • Rabies virus belongs to the Mononegavirales order.
  • Viruses within that order have a negative-sense, single-stranded RNA genome.
  • Rabies virus is a Lyssavirus within the Rhabdoviridae family, distinguishable by its bullet-shaped virions.

Structure and Morphology

  • Rabies virions have a bullet-like shape.
  • They are enveloped viruses with glycoprotein spikes crucial for attachment to host cells.
  • The virus contains a tightly coiled RNA genome within a nucleocapsid.

Characteristics

  • Stability: Sensitive to heat and desiccation (drying).
  • Transmission: Primarily through animal bites (saliva).
  • Neurotropism: Highly infective to the nervous system.
  • Incubation: The time varies significantly.
  • High Mortality: Almost always fatal without intervention.

Cultivation

  • Methods used for cultivation include cell culture (e.g., Vero cells) and animal models (e.g., mice).
  • Cell culture is more commonly used in modern practice.

Replication

  • Attachment and Entry: The virus attaches to host cell receptors and enters through endocytosis.
  • Uncoating: The viral envelope fuses with the host cell, releasing nucleocapsids.
  • Transcription and Translation: The virus's RNA polymerase creates mRNA from the negative-sense RNA genome to translate viral proteins.
  • Replication and Assembly: Viral protein and RNA genomes assemble into new virus particles.
  • Budding: The new particles bud from the host cell to complete the cycle.

Diagnosis

  • Diagnosis involves detecting the virus or viral antigens in infected tissues using techniques such as:
    • Direct Fluorescent Antibody (DFA)
    • Direct Rapid Immunohistochemistry (dRIT)
    • Reverse Transcription-Polymerase Chain Reaction (RT-PCR)
    • Mouse Inoculation Test (MIT)

Prodomal Phase Symptoms

  • Flu-like symptoms: fever, headache, malaise, muscle aches.
  • Discomfort at the bite area: tingling, itching, burning.

Neurological Phase Symptoms

  • Changes in behaviour: anxiety, irritability, restlessness.
  • Agitation, confusion, hallucinations, aggression.
  • Dysphagia (difficulty swallowing) and excessive salivation.
  • Hydrophobia (fear of water): painful spasms of the throat when attempting to swallow.
  • Aerophobia (fear of drafts or air movement).
  • Seizures.
  • Progressive muscle weakness and paralysis.

Prevention and Treatment

  • Animal Vaccination: A critical element for prevention, notably mass dog vaccination programs in affected regions.
  • Post-Exposure Prophylaxis (PEP): Crucial if exposure occurs. Includes wound cleansing, administration of rabies immunoglobulin (RIG) and multiple vaccinations.
  • Early Diagnosis and Treatment: Essential for successful outcomes.

Other Important Information

  • Rabies virus is a member of the Rhabdoviridae family.
  • Effective vaccines reduce risk, proper vaccination is crucial.

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