Josephine was a mutant who with a background in genetics learned from her father was able to understand and use her mutant ability to manipulate the genetic code of other living beings. Little is known of her early years save she inherited a lab, brownstone in NYC and dropped out of high school.
Tricking the X-Factor members Beast and Iceman, that one of her own 'Anti-body' monsters was after her, she watched Beast and Iceman battle the monster, which disintegrated after expending all its power which was a common problem in all her creations. However this fight was but a ruse to get on-board the Skyscraper sized X-Factor Ship. Her attempts to get Iceman to kiss her (and be transformed into an Anti-Body under her control) kept being interrupted by Beast or the other young mutants on the ship, leading to suspicion about her.
After trapping Iceman in a lab she was about to deliver her kiss when the Beast got in the away; their kiss caused an explosion and returned Beast to the intellectual, blue furred, clawed simian appearance he has lost some time before, but with his strength increased. Infectia is then chased off Ship and defeated.
Infectia was created by Louise Simonson and Walter Simonson in 1988 and first appeared in X-Factor # 29.
Later Infectia contracted the fatal Legacy Virus. Beast came to help her but could do nothing to reverse the disease and helped her last request to watch a sunrise. .
Infectia was a mutant with the superhuman ability to see, and manipulate the molecular structure of living beings. She could induce mutations in other living beings by altering them genetically on a molecular level. In each shown instance in which she mutated another she did so by kissing; it is unknown if this was the only method she could use to mutate someone.
Living beings also included plants and she was shown to be able to mutate plants also. She also kissed them to initiate the change.
With her genetics background Infectia could control the mutation process she induces; the transformation takes only seconds. She referred to her victims as ‘Anti-Bodies’. Known types of mutation she has caused include extra mass, size growth, superhuman strength and durability, claws and horns. All know ‘Anti-Bodies’ are subservient to Infectia, though it is unknown if that was a side effect of her power or my choice.
Anti-Bodies powers eventually wear off; the more an Anti-Body uses their power the faster it happens. They all die by disintegration.
Infectia's power did not create a subservient slave when she kissed Beast, rather it reversed alterations to his body and mind by Pestilence. It is not know what would have happened has she kissed other Superhumans, mutant or not.