Vol 31, Part I - forums.sou.edu • Index page - Southern Oregon ...

ABSTRACTS – Symposia
Yersiniae. They promote adherence and internalization to
epithelial cells, resistance to complement, and survival in
macrophages. Even though well studied in enteric Yersiniae,
their role in Y. pestis pathogenesis is unknown. To investigate
the role of Y. pestis OmpX protein, an Ail homologue,
we generated site-directed mutations in ompX and tested
them for loss of any of these phenotypes. Our results demonstrated
that OmpX was required for adherence and internalization
to epithelial cells, and serum resistance. Infection
studies revealed that loss of OmpX delayed the time-to-death
in the mouse infection model of pneumonic plague. Because
murine serum was not bactericidal for the ompX mutant, the
mechanism underlying the delay in time-to-death in mice
may be attributed to loss of adhesion/internalization properties,
but not serum resistance. When OmpX virulence was
assessed in the rat model complete attenuation of virulence
was observed. This highlighted the critical role of serum
resistance in primary pneumonic plague and showed its relevance
for human disease. Additionally, our results showed
that OmpX-mediated serum resistance, adhesiveness, and
invasiveness were dependent on LPS core length, but recombinant
OmpX displayed these functions in E. coli, independently
of other Yersinia proteins and/or LPS. Overall, our
data present an important contribution to understanding
mechanisms of Y. pestis pathogenesis and their significance
to human species.
82 Construction and Characterization of Non-toxic Bacterial
Enterotoxins as Vaccine Adjuvants, LAVANya VEMPATI*
and Juliette Tinker (Department of Biological Sciences,
Boise State University, Science/Nursing Building,
Room 107, Boise, ID 82375; lavanyavempati@gmail.com).
The development of adjuvants that can promote the
delivery of purified subunit vaccines by mucosal routes,
such as the nose or the mouth, is recognized as a top priority
for vaccine research. The bacterial enterotoxins; cholera
toxin (CT) and E.coli heat-labile toxin (LTI), have long
been recognized as powerful adjuvants with the ability to
stimulate specific immune responses to co-administered
antigens when delivered to mucosal surfaces. Shiga toxin 1
(ST1) and pertussis toxin (PT) are structurally homologous
bacterial toxins secreted by Escherichia coli 0157:H7 and
Bordetella pertussis respectively. ST1 and PT also have
reported adjuvant activity. The receptor-binding affinity
and protein stability of these AB5-type toxins appear to be
the basis for their unique immunomodulatory properties.
However, the toxicity of these molecules is a limiting factor
for use as adjuvants in human vaccines. The non-toxic
B subunit of CT, as well as chimeric A 2
B molecules, have
shown much promise as novel mucosal vaccine candidates.
A 2
B chimeras of CT retain the capacity to introduce antigens
into host cells and modulate the immune response,
and toxic domains are replaced with a vaccine antigen of
interest. We have produced ST1 A 2
B chimeras containing
the Yersinia pestis bacterial antigen, LcrV and characterized
antigen uptake in vitro by confocal microscopy. In
addition, we have compared the ability of PTB, ST1B and
CTB to stimulate cytokine production, dendritic cell proliferation
and antigen uptake in vitro. These studies will contribute
to the development of these toxins as novel mucosal
adjuvants.
83 Norovirus Genotype Dynamics Among Outbreak Associated
Strains in Alaska, Idaho, Montana, and Wyoming 2010-
2012, Amanda J Bruesch and CHRISTOPHER L
Ball* (Idaho Bureau of Laboratories, 2220 Old Penitentiary
Road, Boise, ID 83712; ballc1@dhw.idaho.gov).
Noroviruses are thought to cause >90% of viral gastroenteritis
outbreaks worldwide. Noroviruses are one of four
genera in the Caliciviridae. They are categorized into five
genogroups, GI – GV. Strains from genogroups GI, GII, and
GIV are associated with human disease, with GII causing
most outbreaks. Norovirus genogroup II is subdivided into
17 genotypes. The Idaho Bureau of Laboratories provides
Norovirus genotyping for Idaho, Alaska, Montana, and Wyoming
outbreaks as part of the CDC’s national Norovirus subtyping
network, CaliciNet USA.
In 2010, regional Norovirus diversity was low (Simpsons
D=0.28; S=5) with 84% of confirmed outbreaks attributed
to Norovirus GII.4_NewOrleans. In 2011, genotypic
diversity increased (D=0.76; S=7) and genotype GII.1 (32%)
replaced GII.4_NewOrleans (26%) as the most abundant outbreak
genotype. Norovirus evolution is driven by antigenic
drift associated with the development of herd immunity. This
data may suggest a shift in the infectivity of norovirus GII.4_
NewOrleans and the emergence of a new epidemic strain in
the Pacific Northwest.
84 Campylobacter jejuni Exploits Host Cell Processes to
Enhance Disease, Michael E Konkel (Washington
State University, School of Molecular Biosciences, Life Sciences
Bldg, Room 302c, Pullman, WA 99164-7520; konkel@vetmed.wsu.edu).
Campylobacter species are one of the most common
culture-proven causes of human gastrointestinal disease
worldwide, accounting for 400 – 500 million cases of diarrhea
each year. Acute illness is specifically associated with C.
jejuni invasion of intestinal epithelial cells. Accompanying
C. jejuni invasion of the intestinal epithelium is an intense
inflammatory response characterized by the secretion of
interleukin-8 (IL-8) from the epithelial cells. Previous work
has shown that maximal invasion of host cells by C. jejuni is
dependent on synthesis and secretion of proteins termed the
Campylobacter invasion antigens (Cia). We hypothesized
that C. jejuni promotes the activation of intestinal cell signaling
cascades, leading to host cell actin cytoskeletal rearrangements
and the secretion of IL-8. To test this hypothesis,
we infected epithelial cells with a C. jejuni wild-type strain
71