Thymus- The lymphoid organ in which T lymphocytes are educated, mature and multiply.
T lymphocyte cells- thymus dependent cells, coordinate the cell-mediated immune system.
Transcription- constructing a mRNA molecule using a DNA molecule as a template; results in the transfer of genetic information to the mRNA.
Vaccine- Weakened or destroyed microorganisms used to help provide immunity to a certain disease or microorganism and to stimulate the production of antibodies.
Variant- a variation of a particular strain of virus or infective agent; slightly different in form or function.
Vector- anything capable of moving or transferring genetic material.
Viroid- exotic type of virus which only infects plant cells and is simply a group of naked strings of amino acids with no covering.
Virus- infectious organism that replicates itself in the cells of a host; viruses have a half alive/half dead existence and need a host to grow and reproduce.