This family consists of several Clostridium botulinum hemagglutinin (HA) subcomponents. Clostridium botulinum type D strain 4947 produces two different sizes of progenitor toxins (M and L) as intact forms without proteolytic processing. The M toxin is composed of neurotoxin (NT) and nontoxic-nonhemagglutinin (NTNHA), whereas the L toxin is composed of the M toxin and hemagglutinin (HA) subcomponents (HA-70, HA-17, and HA-33) [1].

1: Genetic characterization of Clostridium botulinum type A containing silent type B neurotoxin gene sequences. Hutson RA, Zhou Y, Collins MD, Johnson EA, Hatheway CL, Sugiyama H; J Biol Chem 1996;271:10786-10792. PMID:8631890