Among the notable virulence factor genes hosting the Manila family’s lineage specific SNPs, one mutation was found in mce1B. One study showed that when the mce1 operon was knocked out, the resulting infection was unable to enter a state of persistent infection in mouse lungs, instead exhibiting hypervirulence and killing the mice more rapidly than wild-type Mtb. From ex vivo infection of murine macrophages, this was proposed to have resulted from the mutant failing to stimulate a Th-1 mediated immune response that would have induced protective granuloma formation [37]. This evidence concerns the gene NELFCD and infection.