Antigenic Characterization of <I>Haemophilus somnus</I> Lipooligosaccharide

Lipooligosaccharide (LOS) is the major outer membrane component of many Gram-negative bacteria inhabiting the mucosal membranes, including pathogenic species of <I>Haemophilus</I> and <I>Neisseria</I>. LOS phase variation is one mechanism by which some of these bacteria avoid the host immune response. To better understand LOS phase variation as a virulence mechanism of <I>H. somnus</I>, knowledge of the antigenic diversity of LOS epitopes must be increased. Monoclonal antibodies (MAbs) to <I>H. somnus</I> LOS were produced and used with cross-reacting MAbs to <I>H. aegyptius</I> LOS (MAb 5F5) and <I>Neisseria</I> <I>gonorrhoeae</I> LOS (MAb 3F11) in an ELISA to investigate LOS heterogeneity among forty-five strains of <I>H. somnus</I>. Using three MAbs, thirty-nine of these <I>H. somnus</I> strains were grouped into six antigenic types. Three groups, associated solely with the cross-reacting MAbs 5F5 and 3F11, included the majority (76%) of <I>H. somnus</I> strains. The anti-<I>H. somnus</I> LOS MAb 5D7 recognized a low frequency epitope associated with each of the remaining three groups, which included 11% of the <I>H. somnus</I> strains. Six strains (13%) were not recognized by any of these MAbs. Inhibition ELISA experiments showed that the MAb 5F5 epitope contained phosphocholine (PCho) and this epitope was present in 56% of the strains tested. The MAb 5F5 epitope is phase variable in <I>H. somnus</I> LOS. How PCho negative variants could allow for systemic infection after initial colonization of the mucosa by PCho positive variants is discussed.

Name thesis:degree_name

Master of Science

Level thesis:degree_level

masters

Discipline thesis:degree_discipline

Veterinary Medical Sciences

Department dc:contributor.department

Veterinary Medical Sciences

Grantor dc:publisher

Virginia Tech

Year dc:date.issued

1998

Author dc:creator

• Howard, Michael D.

Chair dc:contributor.committeechair

• Inzana, Thomas J.

Committee members dc:contributor.committeemember

• Schurig, Gerhardt G.
• Nagarkatti, Mitzi

• LOS
• phase variation
• typing scheme
• epitope
• monoclonal antibody

Statement dc:rights

• In Copyright

Licence dc:rights.uri

• http://rightsstatements.org/vocab/InC/1.0/

Dc Identifier Other

etd-101398-081516

OAI identifier oai:identifier

oai:vtechworks.lib.vt.edu:10919/35378