Virology: Host Specificity, Cross-Species Transmission, and Infection Steps

Vocabulary flashcards covering viral exit by membrane fusion, surface glycoproteins, host range and tissue tropism, cross-species transmission (bird flu), reassortment in pigs, and key infection steps (attachment, entry, reverse transcription).

Membrane fusion

Process by which enveloped viruses exit the host cell by fusing the viral envelope with the host cell membrane.

Glycoproteins

Viral surface proteins that determine host range and tissue tropism by binding to receptors on host cells.

Host range

The spectrum of host species a virus can infect, influenced by receptor compatibility and intracellular factors.

Tissue tropism

The specific tissues or cell types a virus preferentially infects within a host.

Bird flu (avian influenza)

Influenza strains that primarily infect birds; can contribute to new strains via interaction with human strains in other hosts.

Pigs as mixing vessels

Pigs can be infected by both avian and human influenza viruses, allowing reassortment and creation of novel strains.

Reassortment

Exchange of genome segments between co-infecting segmented viruses, producing a new virus with mixed traits.

Antigenic shift

Major changes in influenza virus antigens due to reassortment, enabling jump to new host species.

Attachment

First step of infection: virus binds to host cell receptors via surface glycoproteins.

Entry

Second step: virus enters the cell, often by endocytosis or membrane fusion.

Reverse transcription

Synthesis of DNA from viral RNA by reverse transcriptase, a step used by retroviruses after entry.

DNA viruses stability

DNA viruses tend to be genetically more stable due to proofreading, leading to slower antigenic change compared to RNA viruses.