#host cells

[fresherbrine]

COVID-19 SEES YOU

[currentsinbiology]

A new twist on how parasites invade host cells

Humans primarily become infected by eating undercooked meat and poorly washed fruits and vegetables. After infecting the digestive system, the parasite enters deep tissue in the nervous system, among other places, and remains there to develop, nearly undetected.

To do so, T. gondii implements an ingenious invasive strategy. Scientists at the Institute for Advanced Biosciences (IAB) (CNRS/INSERM/Université Grenoble Alpes) have successfully reconstructed the steps taken by the parasite to gain entry to a host cell. T. gondii injects a protein complex into the host cell membrane to form a door through which it passes in a matter of seconds. It then performs a twisting motion to close the door behind itself. This rotational force also allows it to seal itself into a vacuole, a small sac that acts as a nest, where it continues to develop at the host's expense.

Georgios Pavlou, Mateusz Biesaga, Bastien Touquet, Vanessa Lagal, Martial Balland, Alexandre Dufour, Mohamed-ali Hakimi, Isabelle Tardieux. Toxoplasma Parasite Twisting Motion Mechanically Induces Host Cell Membrane Fission to Complete Invasion within a Protective Vacuole. Cell Host & Microbe, 2018; DOI: 10.1016/j.chom.2018.06.003

Once it enters the cell, the parasite rotates to close the door it has opened. This movement also seals it into a vacuole, a sac where it stays and develops.Credit: © Isabelle Tardieux

[studiousness]

viral reproduction

host cells: virus invades and eventually lives off the host by taking over its metabolic machinery.  * viruses cannot reproduce on their own!   * virus attaches to host via cell surface receptors and injects its DNA 

interferon: class of drugs produced by cells in response to viral infections

lytic cycle: eventually kills the host - injects DNA, reproduces, and lyses host cells

lysogenic cycle: virus will replicate its genome, but won't kill the host right away  * fromation of prophage (incorporation of viral DNA into host chromosome)  * during the lysogenic cycle the virus can enter the lytic cycle at any time and kill the host!

HIV (Human Immunodeficiency Virus) - agent of Acquired Immune Deficiency Syndrome (AIDS)

retrovirus - RNA virus that uses an enzyme called reverse transcriptase to synthesise DNA from an RNA strand

infects T4 helper cells

prion: protein infectious particle/misfolded protein that converts other normal proteins into a mutant form  ex: mad cow disease