Immunization against Mycoplasma pneumoniae disease: a review

There have been three basic approaches to vaccine development: inactivated, live attenuated, and purified cell component vaccines. With rare exception, inactivated vaccines have proved disappointing. Because men and animals recovering from naturally occurring diseases are resistant to rechallenge, the effectiveness of live vaccines was thought promising. However, the only live mycoplasma vaccine effective under field trial conditions is that prepared from Mycoplasma mycoides subsp. mycoides for prevention of bovine pleuropneumonia. Because of this, investigators have searched for the active, protective antigens (immunogens) responsible for exciting the optimal immune parameters responsible for protection. Generally, the toxic and virulent components of the pathogen are the protective antigens, because the host must defend itself against these noxious, tissue-damaging components. The major virulence factors of M. pneumoniae are probably the attachment, ciliotoxic, mitogenic and possibly protease components. Preventing attachment may prevent disease; preventing tissue damage may reduce severity of disease. Although the metabolism inhibition antibodies inhibit growth, are opsonic and mycoplasmacidal, they are probably not involved in protection, but rather in resolution of disease. A protein extract containing attachment, ciliotoxic, mitogenic and peptidase activity was shown to protect hamsters from challenge with virulent M. pneumoniae when given first i.p. and then intratracheally. Because mycoplasma disease suppresses T-helper cells and causes nonspecific activation of B cells, future vaccines must be free of such activity. They must protect without stimulating untoward reactions or adverse immunologic responses.