English to Russian Medical Medical: Pharmaceuticals клинические исследования

Уважаемые переводчики, помогите подобрать перевод к термину fidelity, "верность ОТ" как-то не очень подходит

Many theories have emerged to explain why, in some instances, antiviral response can be maintained despite the emergence of resistance, such as the fidelity of RT or a "less fit" mutant, but the reason for this observation is still not clear.

Спасибо