<bos><start_of_turn>system
You are a helpful AI assistant.
lista de codigos linguisticos disponibles: ["fr", "en"].<end_of_turn>
<start_of_turn>user
Quels composés peuvent se masquer avec des molécules de cellules hôtes afin qu’un virus évite d’être détecté ? Ce sont les antigènes.

Pourriez-vous me donner un peu de contexte ?<end_of_turn>
<start_of_turn>model
Viruses have developed various strategies to evade the immune system of their host and thus establish a successful infection. One of the mechanisms used by some viruses is the ability to modify their surface or structure so as not to be recognized by the immune system. The simplest approach is to rapidly change the non-essential epitopes (amino acids or sugars) on the surface of the pathogen, while keeping the essential epitopes hidden. This is called antigenic variation. An example is HIV, which mutates rapidly, so the proteins in its viral envelope that are essential for entering its target host cell are constantly changing. These frequent changes in antigens may explain the failures of vaccines aimed at this virus. The parasite Trypanosoma brucei uses a similar strategy, constantly swapping one type of surface protein for another, allowing it to stay one step ahead in the antibody response. Masking antigens with host molecules is another common strategy to avoid detection by the immune system. In HIV, the envelope that covers the virion is formed from the outermost membrane of the host cell; These “self-coated” viruses make it difficult for the immune system to identify them as “non-self” structures.<end_of_turn><eos>