Intranasal immunization of the combined lipooligosaccharide conjugates protects mice from the challenges with three serotypes of Moraxella catarrhalis.
BACKGROUND
There are no licensed vaccines available against Moraxella catarrhalis, a significant human respiratory pathogen. Lipooligosaccharide (LOS) based conjugate vaccines derived from individual serotype M. catarrhalis only showed partial protection coverage. A vaccine combining LOS conjugates of two or three serotypes might provide a broader protection.


METHODS
Mice were immunized intranasally with the combined conjugates consisting of LOS from serotype A and B or serotype A, B, and C followed by challenge with different M. catarrhalis strains of three serotypes. Mouse lungs, nasal washes, and sera were collected after each challenge for bacterial counts, histological evaluation, cytokine profiles, antibody level and binding activity determinations.


RESULTS
Intranasal administration of the combined LOS conjugates not only enhanced pulmonary bacterial clearance of all three serotypes of M. catarrhalis strains in vaccinated mice, but also elevated serotype-specific anti-LOS immunoglobulin (Ig)A and IgG titers in nasal wash and serum respectively. Mice vaccinated with the combined LOS conjugates also showed increased interferon (IFN)-γ, interleukin (IL)-12, and IL-4 in the lungs after challenges. Compared to the control group, mice immunized with the combined LOS conjugates also showed reduced lung inflammation after M. catarrhalis infections. The hyperimmune sera induced by the combined conjugates exhibited a broad cross-reactivity toward all three serotypes of M. catarrhalis under transmission electron microscopy.


CONCLUSIONS
The combined vaccine of serotype A and B LOS conjugates provides protection against most M. catarrhalis strains by eliciting humoral and cellular immune responses.
Vaccine Research Section, National Institute on Deafness and Other Communication Disorders (NIDCD), National Institutes of Health (NIH), Rockville, Maryland, USA.
Dabin
D
Ren
Hang
H
Xie
Wenhong
W
Zhang
Ferdaus
F
Hassan
Ronald S
RS
Petralia
Shengqing
S
Yu
David J
DJ
Lim
Xin-Xing
XX
Gu
D000281:Administration, Intranasal; D000818:Animals; D000907:Antibodies, Bacterial / Q000096:biosynthesis; D002240:Carbohydrate Sequence; D004797:Enzyme-Linked Immunosorbent Assay; D005260:Female; D018928:Immunity, Mucosal; D007371:Interferon-gamma / Q000378:metabolism; D018664:Interleukin-12 / Q000378:metabolism; D015847:Interleukin-4 / Q000378:metabolism; D008070:Lipopolysaccharides / Q000008:administration & dosage* / Q000737:chemistry; D008168:Lung / Q000378:metabolism; D051379:Mice; D008807:Mice, Inbred BALB C; D016253:Microscopy, Immunoelectron; D008969:Molecular Sequence Data; D001936:Moraxella catarrhalis / Q000276:immunology* / Q000648:ultrastructure; D045828:Moraxellaceae Infections / Q000517:prevention & control*
D000907:Antibodies, Bacterial; D008070:Lipopolysaccharides; C023023:lipid-linked oligosaccharides; D018664:Interleukin-12; D015847:Interleukin-4; D007371:Interferon-gamma