Positive Results From LigoCyte's Norovirus Vaccine Challenge Study Presented at IDSA Annual Meeting

Intranasal Norovirus VLP Vaccine Demonstrates Clinical Efficacy When Compared to Placebo in Phase I/II Trial

BOZEMAN, Montana, October 25, 2010 - LigoCyte Pharmaceuticals, Inc., a private, clinical-stage
biopharmaceuticals company developing innovative vaccine products, today
announced positive results from a Phase I/II challenge study of its norovirus
virus-like particle (VLP) vaccine candidate. Baylor College of Medicine's
Robert Atmar, M.D., the study's principal investigator, shared data from the
trial via an oral presentation at the Infectious Diseases Society of America
(IDSA) 2010 Annual Meeting on October 23 in Vancouver, British Columbia.

"We are extremely pleased with the opportunity to share the important
results from this carefully designed proof-of-concept, multi-center challenge
study. Challenge studies are rigorous tests and we have established for the
first time that immunized subjects can reduce their risk of norovirus illness
by receiving a vaccine," said Donald P. Beeman, Chief Executive Officer. "The
study data are very encouraging, indicating statistically significant
reductions in clinical norovirus illness, infection, and severity of illness
in subjects who received vaccine compared to those who received placebo."

In his presentation, entitled "Efficacy of An Intranasal (IN) Norovirus
(NoV) Vaccine to Prevent Acute Gastroenteritis (AGE) Following Experimental
Live GI.1 NoV Challenge," Dr. Atmar described the challenge study in which 84
adults completed the challenge after receiving two doses of the vaccine or
placebo. The vaccine was generally well tolerated, and demonstrated 47
percent efficacy against any norovirus illness, including mild illness,
(p=0.006) and 26 percent efficacy against norovirus infection (p=0.046). In
the 77 adults who completed the trial as per its original protocol,
vaccination decreased the incidence of AGE due to norovirus from 69.2 percent
to 36.8 percent and the incidence of norovirus infection from 82.1 percent to
60.5 percent. The severity of illness was also significantly reduced in those
vaccinated within the trial (p=0.011).

"At LigoCyte, we are focused on developing a vaccine that has the
potential to help address the critical unmet medical need resulting from the
burden of norovirus illness in both developed and developing countries,"
added Mr. Beeman.

Additional information on LigoCyte's norovirus vaccine program was
presented last week at the Fourth International Conference on Calicivirus
Meeting in Santa Cruz, Chile. In addition, a poster by LigoCyte's Chief
Scientific Officer Robert Bargatze, Ph.D., has been accepted for presentation
at the Keystone Symposia on Immunological Mechanisms of Vaccination to take
place next week in Seattle, Washington.

About Norovirus Infection

Norovirus infection, well known as "the stomach flu," is one of the most
common causes of AGE, afflicting nearly 23 million Americans annually and an
important contributor to gastrointestinal disease worldwide. Norovirus
infection is characterized by the acute onset of nausea, vomiting, abdominal
cramps, diarrhea, and occasionally fever. Noroviruses are highly infective
and easily transmitted. Epidemic outbreaks occur in community environments,
particularly hospitals, hotels, schools, day care facilities and nursing
homes, with mounting socioeconomic cost to families, the health care system
and businesses. Military units are significantly affected when the virus
strikes, as outbreaks impact combat readiness. Severe clinical outcomes are
associated with at-risk populations such as immunocompromised individuals
where complications caused by infection can disrupt primary treatment
regimens and even lead to death.

About the Phase I/II Norovirus Vaccine Study

The Phase I/II randomized, double blind, multi-center, placebo-controlled
safety and efficacy study was designed to evaluate the norovirus monovalent
GI.1 VLP vaccine versus placebo in approximately 90 healthy adult volunteers
between the ages of 18 and 50 years. The study consisted of two stages: the
Vaccination Stage with post-vaccination follow-up, followed by the Challenge
Stage with post-challenge follow-up. Subjects received a two-dose intranasal
regimen of either the vaccine or placebo on Days 0 and 21 and were evaluated
for vaccine safety and immune responses. On or after Study Day 42, subjects
were admitted to an inpatient nursing unit, challenged with live norovirus,
held in the unit for at least four days following challenge and then followed
for post-challenge safety and efficacy with multiple clinical assessments and
collection of stool specimens. The study was conducted at Baylor College of
Medicine, the University of Cincinnati and Cincinnati Children's Hospital
Medical Center, the Johns Hopkins School of Medicine and SNBL CPC, Inc., a
clinical research organization in Baltimore, MD.

About LigoCyte's Intranasal Norovirus Vaccine Candidate

LigoCyte's intranasal norovirus vaccine is a dry powder formulation
containing virus-like particle (VLP) antigens representing the live virus
while lacking the ability to reproduce or cause illness. VLPs mimic the
natural virus by preserving the authentic structure of the viral capsid (the
shell of protein that protects the nucleic acid of a virus). LigoCyte's
vaccine formulation also includes the adjuvant Monophosphoryl Lipid A,
provided under license from GlaxoSmithKline (NYSE: GSK), and the nasal
vaccine incorporates chitosan. This application of chitosan (ChiSys(R)) has
been licensed from Archimedes Development Ltd.(1)

A clinical study of an intramuscular bivalent formulation of LigoCyte's
norovirus vaccine is ongoing.

About LigoCyte

LigoCyte is a private, clinical-stage biopharmaceutical company focused
on developing novel vaccines for gastrointestinal and respiratory
indications. LigoCyte's expertise in virus-like particle technology supports
a pipeline of enhanced product candidates, including vaccines against
norovirus, influenza and respiratory syncytial virus. LigoCyte has funded its
product development efforts through a mix of private investment as well as
grants and contracts administered through the National Institutes of Health
and the U.S. Department of Defense, including a recent US$3.6 million
commitment from the agency. LigoCyte's investors include Forward Ventures,
JAFCO, Novartis Venture Fund, Fidelity Biosciences, MedImmune Ventures,
Athenian Venture Partners and MC Life Sciences Ventures (Mitsubishi
International Corporation). The company closed its most recent financing in
October 2010 from its existing venture investors. GlaxoSmithKline is also a
shareholder of the company. For additional information on LigoCyte, please
visit www.ligocyte.com.

(1) ChiSys is a trademark of Archimedes Development Ltd., and is
registered as a CTM, as a U.S. Registered Trademark and in certain other
jurisdictions.

Jamie Lacey-Moreira, PressComm PR, LLC, +1-410-299-3310, jamielacey at presscommpr.com