Role of lipopolysaccharide and a major outer membrane protein from Francisella tularensis in the induction of immunity against tularemia

A conserved and immunodominant lipoprotein of Francisella tularensis is proinflammatory but not essential for virulence

“…In addition, mice can be immunized against F. tularensis LVS by administration of its purified LPS alone [49,50]. The observations that LpnA stimulates T cells of individuals previously exposed to F. tularensis [31] and that it can confer partial resistance to challenge with the LVS when given to mice in recombinant form [32,48] suggested a potentially important role for the lipoprotein in acquired immunity to F. tularensis.…”

Purified Lipopolysaccharide fromFrancisella tularensisLive Vaccine Strain (LVS) Induces Protective Immunity against LVS Infection That Requires B Cells and Gamma Interferon

“…Previous studies clearly indicated that immunization of mice with heat-killed LVS, for instance, did not provide any measurable protection against challenge with either LVS or fully virulent F. tularensis strain Schu 4 (5,11,20,22). Of note in this regard is the fact that another study using repeated large doses of LVS LPS as a vaccine demonstrated protection against lethal LVS challenge but not Schu 4 (19,20) challenge. These and other early studies have led to the proposal that Francisella subunit vaccines and various extracts of bacteria may provide some weak protection against challenge with LVS or less virulent strains of F. tularensis but not against more virulent strains such as Schu 4.…”

“…Further, detection of antibodies to Francisella LPS has been useful in diagnosis of human disease from natural infection (37,42) as well as in demonstrating successful vaccination with LVS (44), indicating that Francisella LPS is immunogenic. Mice given repeated large doses of LVS LPS were protected against lethal LVS infection (19). The latter finding is particularly intriguing, since protection against intracellular pathogens has often been more difficult to achieve using killed bacteria or purified bacterial components than through infection with live attenuated organisms.…”

Characterization of the O antigen gene cluster and structural analysis of the O antigen of Francisella tularensis subsp. tularensis

“…holarctica are fully protected against a subsequent challenge with a subsp. holarctica strain (Fulop et al, 1995), but not against challenge with a subsp. tularensis strain (Fulop et al, 2001).…”