title: Frequency and fitness consequences of bacteriophage φ6 host range mutations.
abstract: Viruses readily mutate and gain the ability to infect novel hosts, but few data are available regarding the number of possible host range-expanding mutations allowing infection of any given novel host, and the fitness consequences of these mutations on original and novel hosts. To gain insight into the process of host range expansion, we isolated and sequenced 69 independent mutants of the dsRNA bacteriophage Φ6 able to infect the novel host, Pseudomonas pseudoalcaligenes. In total, we found at least 17 unique suites of mutations among these 69 mutants. We assayed fitness for 13 of 17 mutant genotypes on P. pseudoalcaligenes and the standard laboratory host, P. phaseolicola. Mutants exhibited significantly lower fitnesses on P. pseudoalcaligenes compared to P. phaseolicola. Furthermore, 12 of the 13 assayed mutants showed reduced fitness on P. phaseolicola compared to wildtype Φ6, confirming the prevalence of antagonistic pleiotropy during host range expansion. Further experiments revealed that the mechanistic basis of these fitness differences was likely variation in host attachment ability. In addition, using computational protein modeling, we show that host-range expanding mutations occurred in hotspots on the surface of the phage's host attachment protein opposite a putative hydrophobic anchoring domain.
authors.affiliation: Biology Department, Queens College of the City University of New York, New York, New York, United States of America; The Graduate Center of the City University of New York, New York, New York, United States of America.
authors.forename: Brian E
authors.initials: BE
authors.lastname: Ford
authors.affiliation: Biology Department, Queens College of the City University of New York, New York, New York, United States of America.
authors.forename: Bruce
authors.initials: B
authors.lastname: Sun
authors.affiliation: Biology Department, Queens College of the City University of New York, New York, New York, United States of America.
authors.forename: James
authors.initials: J
authors.lastname: Carpino
authors.affiliation: Biology Department, Queens College of the City University of New York, New York, New York, United States of America.
authors.forename: Elizabeth S
authors.initials: ES
authors.lastname: Chapler
authors.affiliation: Biology Department, Queens College of the City University of New York, New York, New York, United States of America.
authors.forename: Jane
authors.initials: J
authors.lastname: Ching
authors.affiliation: Biology Department, Queens College of the City University of New York, New York, New York, United States of America.
authors.forename: Yoon
authors.initials: Y
authors.lastname: Choi
authors.affiliation: Biology Department, Queens College of the City University of New York, New York, New York, United States of America.
authors.forename: Kevin
authors.initials: K
authors.lastname: Jhun
authors.affiliation: Biology Department, Queens College of the City University of New York, New York, New York, United States of America.
authors.forename: Jung D
authors.initials: JD
authors.lastname: Kim
authors.affiliation: Biology Department, Queens College of the City University of New York, New York, New York, United States of America.
authors.forename: Gregory G
authors.initials: GG
authors.lastname: Lallos
authors.affiliation: Biology Department, Queens College of the City University of New York, New York, New York, United States of America.
authors.forename: Rachelle
authors.initials: R
authors.lastname: Morgenstern
authors.affiliation: Biology Department, Queens College of the City University of New York, New York, New York, United States of America.
authors.forename: Shalini
authors.initials: S
authors.lastname: Singh
authors.affiliation: Biology Department, Queens College of the City University of New York, New York, New York, United States of America.
authors.forename: Sai
authors.initials: S
authors.lastname: Theja
authors.affiliation: Biology Department, Queens College of the City University of New York, New York, New York, United States of America.
authors.forename: John J
authors.initials: JJ
authors.lastname: Dennehy
mesh_terms: D017126:Bacteriophage phi 6 / Q000235:genetics* / Q000502:physiology; D001665:Binding Sites; D056084:Genetic Fitness; D058507:Host Specificity; D008958:Models, Molecular; D059645:Mutation Rate; D044205:Pseudomonas pseudoalcaligenes / Q000235:genetics / Q000821:virology*; D017423:Sequence Analysis, RNA; D014764:Viral Proteins / Q000737:chemistry / Q000235:genetics*
chemical_list: D014764:Viral Proteins