A new DNA-cloning vector for Haemophilus influenzae Rd.

A new, high-efficiency, DNA-cloning vector pJ1-8 was derived in two steps from the chimeric plasmid pD7 consisting of RSF 0885 (ampr) and Haemophilus influenzae chromosomal DNA. pJl-8 has only one EcoRI site and a molecular weight of only 2.5 × 106. No detectable ampr transformation was obtained with pJl-8 DNA. However, ampr transformation increases markedly if Haemophilus influenzae chromosomal DNA segments are spliced into it, providing a very facile assay for detecting inserts.