B2 Flashcards
(17 cards)
What is a null infection in the context of viral infection in vitro?
A null infection occurs when a virus cannot attach to or penetrate the cell, resulting in no infection.
What is an abortive infection?
An abortive infection occurs when a virus can enter the cell but cannot produce infectious progeny, often because the cell is non-permissive.
What is a cytopathic effect in viral infection?
A cytopathic effect refers to cell damage or death caused by viral infection through mechanisms such as lysis or apoptosis.
How does cell fusion occur during a viral infection?
During a viral infection, cell fusion can occur, leading to the formation of a syncytium, a multi-nucleated cell formed by the fusion of infected cells.
What is a persistent infection in vitro?
A persistent infection occurs when the virus replicates and continuously releases progeny while the cell or cell population survives.
Define latent infection in the context of viral infection.
In a latent infection, the viral genome remains in the cell without producing progeny until it is reactivated.
What does transformation mean in viral infection?
Transformation refers to the process by which viral infection results in the immortalisation of a cell line, indicating that the cell is permissive.
What are the primary components of the innate immune response to viral infection?
The innate response includes natural killer cells and interferons (IFNα, IFNβ, IFNγ).
How do NK cells recognise infected cells?
NK cells recognise infected cells by detecting alterations or absence of MHC class I molecules, triggering the release of cytotoxic granules.
What is the role of interferons in viral infection?
Interferons inhibit viral replication, activate immune cells, enhance antigen presentation, and induce an antiviral state in target cells.
Name the three major antiviral effector molecules (AVEM) in interferon response.
PKR (dsRNA-dependent protein kinase), OAS (oligo A synthetase), and RNAse L.
What is antibody-dependent cellular cytotoxicity (ADCC)?
ADCC is the destruction of virus-infected cells by immune cells (e.g., NK cells, macrophages) that recognise antibodies bound to viral antigens on infected cells.
What are the three primary antibody isotypes involved in antiviral responses?
IgM (early infection indicator), IgA (mucosal immunity), and IgG (systemic immunity and placental transfer).
: What is antigenic drift?
Antigenic drift involves small mutations in viral surface proteins, such as hemagglutinin, allowing the virus to evade neutralising antibodies.
What is antigenic shift?
Antigenic shift occurs when RNA segments are exchanged between different viral strains, creating a novel virus against which the host has little to no immunity.
How can viruses evade immune responses passively?
Passive evasion includes antigenic variation, compartmentalisation (e.g., neurons for HSV), and latency without antigen production.
How do some viruses actively evade immune responses?
Active evasion involves interfering with IFN signalling (e.g., HCV) or blocking MHC antigen presentation (e.g., HSV).
