Growth of bacteriophage phiX-174 at elevated temperatures

The replication of bacteriophage phiX-174 is impaired at temperatures above 40 degrees C. Mutants (ht) that replicate at high temperature were isolated and partially characterized. Wild-type phiX fails to grow at high temperature because, unlike the mutants, it does not make appreciable amounts of single-stranded (ss)DNA. An unusual form of ssDNA, not found in complete virions, is described.