Second site escape of a T20-dependent HIV-1 variant by a single amino acid change in the CD4 binding region of the envelope glycoprotein
<p>Abstract</p> <p>Background</p> <p>We previously described the selection of a T20-dependent human immunodeficiency virus type-1 (HIV-1) variant in a patient on T20 therapy. The fusion inhibitor T20 targets the viral envelope (Env) protein by blocking a conformational...
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| Format: | Article |
| Language: | English |
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BMC
2006-11-01
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| Series: | Retrovirology |
| Online Access: | http://www.retrovirology.com/content/3/1/84 |
| _version_ | 1811277613643071488 |
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| author | Berkhout Ben Baldwin Chris E |
| author_facet | Berkhout Ben Baldwin Chris E |
| author_sort | Berkhout Ben |
| collection | DOAJ |
| description | <p>Abstract</p> <p>Background</p> <p>We previously described the selection of a T20-dependent human immunodeficiency virus type-1 (HIV-1) variant in a patient on T20 therapy. The fusion inhibitor T20 targets the viral envelope (Env) protein by blocking a conformational switch that is critical for viral entry into the host cell. T20-dependent viral entry is the result of 2 mutations in Env (GIA-SKY), creating a protein that undergoes a premature conformational switch, and the presence of T20 prevents this premature switch and rescues viral entry. In the present study, we performed 6 independent evolution experiments with the T20-dependent HIV-1 variant in the absence of T20, with the aim to identify second site compensatory changes, which may provide new mechanistic insights into Env function and the T20-dependence mechanism.</p> <p>Results</p> <p>Escape variants with improved replication capacity appeared within 42 days in 5 evolution cultures. Strikingly, 3 cultures revealed the same single amino acid change in the CD4 binding region of Env (glycine at position 431 substituted for arginine: G431R). This mutation was sufficient to abolish the T20-dependence phenotype and restore viral replication in the absence of T20. The GIA-SKY-G431R escape variant produces an Env protein that exhibits reduced syncytia formation and reduced cell-cell fusion activity. The escape variant was more sensitive to an antibody acting on an early gp41 intermediate, suggesting that the G431R mutation helps preserve a pre-fusion Env conformation, similar to T20 action. The escape variant was also less sensitive to soluble CD4, suggesting a reduced CD4 receptor affinity.</p> <p>Conclusion</p> <p>The forced evolution experiments indicate that the premature conformational switch of the T20-dependent HIV-1 Env variant (GIA-SKY) can be corrected by a second site mutation in Env (GIA-SKY-G431R) that affects the interaction with the CD4 receptor.</p> |
| first_indexed | 2024-04-13T00:19:53Z |
| format | Article |
| id | doaj.art-1b2813565d8e4b31b84ccdc8316938fb |
| institution | Directory Open Access Journal |
| issn | 1742-4690 |
| language | English |
| last_indexed | 2024-04-13T00:19:53Z |
| publishDate | 2006-11-01 |
| publisher | BMC |
| record_format | Article |
| series | Retrovirology |
| spelling | doaj.art-1b2813565d8e4b31b84ccdc8316938fb2022-12-22T03:10:49ZengBMCRetrovirology1742-46902006-11-01318410.1186/1742-4690-3-84Second site escape of a T20-dependent HIV-1 variant by a single amino acid change in the CD4 binding region of the envelope glycoproteinBerkhout BenBaldwin Chris E<p>Abstract</p> <p>Background</p> <p>We previously described the selection of a T20-dependent human immunodeficiency virus type-1 (HIV-1) variant in a patient on T20 therapy. The fusion inhibitor T20 targets the viral envelope (Env) protein by blocking a conformational switch that is critical for viral entry into the host cell. T20-dependent viral entry is the result of 2 mutations in Env (GIA-SKY), creating a protein that undergoes a premature conformational switch, and the presence of T20 prevents this premature switch and rescues viral entry. In the present study, we performed 6 independent evolution experiments with the T20-dependent HIV-1 variant in the absence of T20, with the aim to identify second site compensatory changes, which may provide new mechanistic insights into Env function and the T20-dependence mechanism.</p> <p>Results</p> <p>Escape variants with improved replication capacity appeared within 42 days in 5 evolution cultures. Strikingly, 3 cultures revealed the same single amino acid change in the CD4 binding region of Env (glycine at position 431 substituted for arginine: G431R). This mutation was sufficient to abolish the T20-dependence phenotype and restore viral replication in the absence of T20. The GIA-SKY-G431R escape variant produces an Env protein that exhibits reduced syncytia formation and reduced cell-cell fusion activity. The escape variant was more sensitive to an antibody acting on an early gp41 intermediate, suggesting that the G431R mutation helps preserve a pre-fusion Env conformation, similar to T20 action. The escape variant was also less sensitive to soluble CD4, suggesting a reduced CD4 receptor affinity.</p> <p>Conclusion</p> <p>The forced evolution experiments indicate that the premature conformational switch of the T20-dependent HIV-1 Env variant (GIA-SKY) can be corrected by a second site mutation in Env (GIA-SKY-G431R) that affects the interaction with the CD4 receptor.</p>http://www.retrovirology.com/content/3/1/84 |
| spellingShingle | Berkhout Ben Baldwin Chris E Second site escape of a T20-dependent HIV-1 variant by a single amino acid change in the CD4 binding region of the envelope glycoprotein Retrovirology |
| title | Second site escape of a T20-dependent HIV-1 variant by a single amino acid change in the CD4 binding region of the envelope glycoprotein |
| title_full | Second site escape of a T20-dependent HIV-1 variant by a single amino acid change in the CD4 binding region of the envelope glycoprotein |
| title_fullStr | Second site escape of a T20-dependent HIV-1 variant by a single amino acid change in the CD4 binding region of the envelope glycoprotein |
| title_full_unstemmed | Second site escape of a T20-dependent HIV-1 variant by a single amino acid change in the CD4 binding region of the envelope glycoprotein |
| title_short | Second site escape of a T20-dependent HIV-1 variant by a single amino acid change in the CD4 binding region of the envelope glycoprotein |
| title_sort | second site escape of a t20 dependent hiv 1 variant by a single amino acid change in the cd4 binding region of the envelope glycoprotein |
| url | http://www.retrovirology.com/content/3/1/84 |
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