Trong phiên bản cập nhật của VircoTYPE, tất cả các đột biến và cặp đột biến của virus của bệnh nhân đóng góp cho kháng thuốc cụ thể theo mô hình hồi quy tuyến tính nhiều được xác định. Họ sau đó được bao gồm trong mô hình hồi quy tuyến tính tương ứng bằng cách sử dụng các yếu tố trọng lượng thuốc kháng cụ thể của các đột biến quan sát | Background 333 virtual phenotype. For the VircoType interpretation genotypes matching the patient s virus were identified through a database search. The IC50 results of each of the matching viruses were averaged thus producing the probable phenotype of the patient s virus. In the updated version of VircoTYPE all mutations and mutation pairs of the patient s virus that contribute to specific drug resistance according to the new multiple linear regression modeling are identified. They are then included in the respective linear regression model using the drug specific resistance weight factors of the observed mutations and mutation pairs. The outcome variable of the regression model is the predicted fold-change comparing the IC50 of the patient s virus to the IC50 of the wild type reference virus. In addition machine learning approaches such as decision trees and support vector machines as implemented by the geno2pheno system can be applied to predict phenotypic drug resistance Beerenwinkel 2003 Larder 2005 . Some of the most important databases for resistance profiles and interpretational systems are available free of charge on the following websites Stanford-Database http id 24 Los Alamos-Database http id 25 geno2pheno http id 26 HIV Genotypic Drug Resistance Interpretation - ANRS AC11 http id 138 HIV-GRADE http cms grade Some commercial suppliers of resistance tests also provide interpretation guidelines for their systems . TruGene GeneSeq Retrogram . The discussion about genotypic resistance in this chapter focuses on the sequencing of the reverse transcriptase the protease and the env gp41 gene and on the respective resistance patterns that emerge with treatment. Most data are derived from patients with subtype B viruses representing only 12 of the worldwide HIV-infected population . However by now non-subtype B viruses have also been investigated for the .
