Alteration of the genome of a cell by direct introduction of DNA, a small portion of which becomes covalently associated with the host cell DNA.


A gene construct introduced into an organism by human intervention.


The enzyme responsible for moving a transposon from one place to another.


A DNA element capable of moving (transposing) from one location in a genome to another in the same cell through the action of transposase.

Trojan gene

A gene that drives a population to extinction during the process of spread as a result of destructive, self-reinforcing cycles of natural selection.


A type of DNA, such as a plasmid or phage that is self-replicating and that can be used to transfer DNA segments among host cells. Also, an insect or other organism that provides a means of dispersal for a disease or parasite.

Vertical transmission

Inheritance of a gene from parent to offspring.


Virus in blood.


The extracellular form of a virus (i.e., a virus particle).


Transplantation of cells, tissues, or organs from one species to another.

Zoonotic infection

Transmission of an infectious agent from an animal reservoir to humans.


A fertilized oocyte.

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