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Viral protein U ( Vpu ) is a protein encoded by human immunodeficiency virus type 1 ( HIV - 1 ) that promotes the degradation of the virus receptor , CD4 , and enhances the release of virus particles from cells .
 GENE: Viral protein U; GENE: Vpu; GENE: CD4
Please list all entity words in the text that fit the category.Output format is "type1: word1; type2: word2". 
Option: GENE 
Text: {0} 
Answer:
 GENE: Viral protein U; GENE: Vpu; GENE: CD4