Phylogenetic dependency networks: inferring patterns of CTL escape and codon covariation in HIV-1 Gag.

HIV avoids elimination by cytotoxic T-lymphocytes (CTLs) through the evolution of escape mutations. Although there is mounting evidence that these escape pathways are broadly consistent among individuals with similar human leukocyte antigen (HLA) class I alleles, previous population-based studies ha...

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Autores principales: Jonathan M Carlson, Zabrina L Brumme, Christine M Rousseau, Chanson J Brumme, Philippa Matthews, Carl Kadie, James I Mullins, Bruce D Walker, P Richard Harrigan, Philip J R Goulder, David Heckerman
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Publicado: Public Library of Science (PLoS) 2008
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Acceso en línea:https://doaj.org/article/e61b6ed8a25c42d0982ce1e881a1fc15
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spelling oai:doaj.org-article:e61b6ed8a25c42d0982ce1e881a1fc152021-12-02T19:57:54ZPhylogenetic dependency networks: inferring patterns of CTL escape and codon covariation in HIV-1 Gag.1553-734X1553-735810.1371/journal.pcbi.1000225https://doaj.org/article/e61b6ed8a25c42d0982ce1e881a1fc152008-11-01T00:00:00Zhttps://www.ncbi.nlm.nih.gov/pmc/articles/pmid/19023406/?tool=EBIhttps://doaj.org/toc/1553-734Xhttps://doaj.org/toc/1553-7358HIV avoids elimination by cytotoxic T-lymphocytes (CTLs) through the evolution of escape mutations. Although there is mounting evidence that these escape pathways are broadly consistent among individuals with similar human leukocyte antigen (HLA) class I alleles, previous population-based studies have been limited by the inability to simultaneously account for HIV codon covariation, linkage disequilibrium among HLA alleles, and the confounding effects of HIV phylogeny when attempting to identify HLA-associated viral evolution. We have developed a statistical model of evolution, called a phylogenetic dependency network, that accounts for these three sources of confounding and identifies the primary sources of selection pressure acting on each HIV codon. Using synthetic data, we demonstrate the utility of this approach for identifying sites of HLA-mediated selection pressure and codon evolution as well as the deleterious effects of failing to account for all three sources of confounding. We then apply our approach to a large, clinically-derived dataset of Gag p17 and p24 sequences from a multicenter cohort of 1144 HIV-infected individuals from British Columbia, Canada (predominantly HIV-1 clade B) and Durban, South Africa (predominantly HIV-1 clade C). The resulting phylogenetic dependency network is dense, containing 149 associations between HLA alleles and HIV codons and 1386 associations among HIV codons. These associations include the complete reconstruction of several recently defined escape and compensatory mutation pathways and agree with emerging data on patterns of epitope targeting. The phylogenetic dependency network adds to the growing body of literature suggesting that sites of escape, order of escape, and compensatory mutations are largely consistent even across different clades, although we also identify several differences between clades. As recent case studies have demonstrated, understanding both the complexity and the consistency of immune escape has important implications for CTL-based vaccine design. Phylogenetic dependency networks represent a major step toward systematically expanding our understanding of CTL escape to diverse populations and whole viral genes.Jonathan M CarlsonZabrina L BrummeChristine M RousseauChanson J BrummePhilippa MatthewsCarl KadieJames I MullinsBruce D WalkerP Richard HarriganPhilip J R GoulderDavid HeckermanPublic Library of Science (PLoS)articleBiology (General)QH301-705.5ENPLoS Computational Biology, Vol 4, Iss 11, p e1000225 (2008)
institution DOAJ
collection DOAJ
language EN
topic Biology (General)
QH301-705.5
spellingShingle Biology (General)
QH301-705.5
Jonathan M Carlson
Zabrina L Brumme
Christine M Rousseau
Chanson J Brumme
Philippa Matthews
Carl Kadie
James I Mullins
Bruce D Walker
P Richard Harrigan
Philip J R Goulder
David Heckerman
Phylogenetic dependency networks: inferring patterns of CTL escape and codon covariation in HIV-1 Gag.
description HIV avoids elimination by cytotoxic T-lymphocytes (CTLs) through the evolution of escape mutations. Although there is mounting evidence that these escape pathways are broadly consistent among individuals with similar human leukocyte antigen (HLA) class I alleles, previous population-based studies have been limited by the inability to simultaneously account for HIV codon covariation, linkage disequilibrium among HLA alleles, and the confounding effects of HIV phylogeny when attempting to identify HLA-associated viral evolution. We have developed a statistical model of evolution, called a phylogenetic dependency network, that accounts for these three sources of confounding and identifies the primary sources of selection pressure acting on each HIV codon. Using synthetic data, we demonstrate the utility of this approach for identifying sites of HLA-mediated selection pressure and codon evolution as well as the deleterious effects of failing to account for all three sources of confounding. We then apply our approach to a large, clinically-derived dataset of Gag p17 and p24 sequences from a multicenter cohort of 1144 HIV-infected individuals from British Columbia, Canada (predominantly HIV-1 clade B) and Durban, South Africa (predominantly HIV-1 clade C). The resulting phylogenetic dependency network is dense, containing 149 associations between HLA alleles and HIV codons and 1386 associations among HIV codons. These associations include the complete reconstruction of several recently defined escape and compensatory mutation pathways and agree with emerging data on patterns of epitope targeting. The phylogenetic dependency network adds to the growing body of literature suggesting that sites of escape, order of escape, and compensatory mutations are largely consistent even across different clades, although we also identify several differences between clades. As recent case studies have demonstrated, understanding both the complexity and the consistency of immune escape has important implications for CTL-based vaccine design. Phylogenetic dependency networks represent a major step toward systematically expanding our understanding of CTL escape to diverse populations and whole viral genes.
format article
author Jonathan M Carlson
Zabrina L Brumme
Christine M Rousseau
Chanson J Brumme
Philippa Matthews
Carl Kadie
James I Mullins
Bruce D Walker
P Richard Harrigan
Philip J R Goulder
David Heckerman
author_facet Jonathan M Carlson
Zabrina L Brumme
Christine M Rousseau
Chanson J Brumme
Philippa Matthews
Carl Kadie
James I Mullins
Bruce D Walker
P Richard Harrigan
Philip J R Goulder
David Heckerman
author_sort Jonathan M Carlson
title Phylogenetic dependency networks: inferring patterns of CTL escape and codon covariation in HIV-1 Gag.
title_short Phylogenetic dependency networks: inferring patterns of CTL escape and codon covariation in HIV-1 Gag.
title_full Phylogenetic dependency networks: inferring patterns of CTL escape and codon covariation in HIV-1 Gag.
title_fullStr Phylogenetic dependency networks: inferring patterns of CTL escape and codon covariation in HIV-1 Gag.
title_full_unstemmed Phylogenetic dependency networks: inferring patterns of CTL escape and codon covariation in HIV-1 Gag.
title_sort phylogenetic dependency networks: inferring patterns of ctl escape and codon covariation in hiv-1 gag.
publisher Public Library of Science (PLoS)
publishDate 2008
url https://doaj.org/article/e61b6ed8a25c42d0982ce1e881a1fc15
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