| A SCIENTIST'S 20-YEAR UNFINISHED JOURNEY
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| | but as soon as you stop the therapy, the
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| TO TREAT HBV MAY OPEN THE DOOR TO A NEW
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| | virus comes right back up." He told us
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| CLASS OF FLEXIBLE VACCINESWhile preparing
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| | the sustained viral response is only
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| a lecture in biochemistry and virology
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| | about two to three percent. Only about 30
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| for his graduate students at the
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| | percent remain free of the virus, about
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| University of Alberta in the early 1980s,
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| | one year after patients have stopped
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| Dr. Lorne Tyrrell ran across a study just
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| | taking lamivudine."How do you break
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| published in the medical journal, Cell.
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| | tolerance?" Tyrrell asked himself, hoping
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| The research by William Mason and Jesse
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| | to develop a way to stimulate an immune
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| Summers, entitled "Replication of
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| | response. All of the patients, he had
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| Hepatitis B," discussed their study of
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| | observed, seemed to be tolerant of the
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| the hepatitis B virus in infected duck
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| | hepatitis B virus. He pondered the
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| liver.After studying their duck model
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| | dilemma, "Was there some way to break
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| theory, Tyrrell speculated if the
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| | tolerance to hepatitis B by stimulating
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| hepatitis B virus (HBV) might be
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| | the immune response?" Tyrrell studied
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| susceptible to antiviral agents, and
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| | what others were attempting and wasn't
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| consulted with a colleague, who
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| | satisfied with the approaches others were
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| specialized in nucleoside chemistry. Both
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| | taking to stimulate immune response. His
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| medical professors became excited about
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| | ViRexx Medical research team brainstormed
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| the possibility of inhibiting the HBV
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| | about different ways to target the
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| virus with nucleoside analogues. Thus
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| | antigen into the dendritic cells."That's
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| began the infectious disease specialist's
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| | where we came in with the Chimigen (TM)
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| first leg of a journey, which led to the
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| | technology," Tyrrell said. "The dendritic
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| use of lamivudine as a therapy for
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| | cells have receptors on their surface
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| chronic HBV infections.More than 350
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| | that will bind the Fc portion of an
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| million people across the world,
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| | antibody." He pointed out a key feature
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| especially in Asia, now had new hope,
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| | of the Chimigen (TM) platform, "We used
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| some for their lifelong infections
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| | the Fc portion of a murine (mouse)
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| contracted vertically at birth from their
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| | antibody to hook onto our hepatitis B
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| mothers. In 2003, the Center for Disease
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| | antigens. This would direct the viral
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| Control estimated 73,000 Americans were
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| | antigens into dendritic cells in vivo."
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| infected with HBV, and about 5,000 die
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| | Because the dendritic cells are the
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| each year from sickness caused by HBV. It
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| | sentries of the immune system, they guard
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| is reportedly 100 times more contagious
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| | what comes in. Recognizing a 'foreign
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| than the AIDS virus. Many in North
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| | situation' in the murine antibody, it
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| America, who had been infected with the
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| | treats the whole molecule including the
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| virus from sexual transmission or
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| | virus antigen as foreign.LINK RECOGNITION
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| intravenous drug use, were offered a
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| | MAY HOLD THE KEYDr. Rajan George, ViRexx
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| potentially life-saving therapy.Licensed
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| | Medical's vice president of research and
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| in 1998, lamivudine is now used in 120
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| | development, told us, "The dendritic
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| countries as a standard therapy for
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| | cells chop up this protein into small
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| chronic HBV carriers. The compound is
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| | pieces called peptides, also known as
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| also used in combination with other
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| | epitopes. The dendritic cells have a
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| drugs, such as protease inhibitors, for
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| | system where they put the T-cell epitope
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| HIV therapy. Development rights were
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| | on another protein, MHC Class I, and
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| licensed to Glaxo Wellcome in 1990, which
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| | bring it to the surface of the dendritic
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| is now sold under the brand name
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| | cell. They are presented as a complex on
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| Epivir(R). For his pioneering efforts in
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| | the surface of the dendritic cell to
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| developing the antiviral agent, Dr.
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| | attract the T-cells." When the T-cells
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| Tyrrell was awarded the gold medal by the
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| | arrive to inspect the foreign entity, the
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| Canadian Liver Foundation and the
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| | cytotoxic T-cells are activated. Then,
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| Canadian Association for the Study of
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| | they begin attacking and killing the
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| Liver in 2000. In 2005, he won the
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| | virus-infected cells.Research at Tokyo's
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| prestigious EnCana Principal Award for
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| | Cancer Institute Hospital, published in
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| his development of the first effective
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| | 1987 in Nippon Sanka Fujinka Gakkai
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| oral medication for Hepatitis B.HIS
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| | Zasshi, suggested a feasibility of linked
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| UNANSWERED QUESTIONS LAUNCHED A NEW HBV
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| | recognition of a virus antigen as a
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| INVESTIGATIONDespite the awards and
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| | helper in tumor immunity with a target
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| recognition, questions remained for Dr.
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| | antigen. In the case of ViRexx Medical,
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| Tyrrell about the shortcomings of
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| | Tyrrell's team has created a new
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| lamivudine. He was troubled that some
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| | molecule, called "chimigen." The term is
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| viruses would develop resistance to the
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| | shorthand for a chimeric antigen, meaning
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| compound. "I was disappointed the
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| | it is an antigen created from two
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| sustained viral response was not
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| | different sources, part virus and part
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| complete," Tyrrell told us. In April
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| | murine monoclonal antibody.Dr. Tyrrell's
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| 2003, the Journal of Antimicrobial
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| | work at ViRexx Medical with Dr. George
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| Chemotherapy published a study in Japan
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| | suggested the linked-recognition theory
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| showing, "long-term (lamivudine) therapy
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| | might be the key to breaking tolerance.
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| is associated with increased emergence of
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| | Dr. George emphasized, "The new
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| lamivudine-resistant strains of HBV."
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| | 'chimigen' stimulates an immune response
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| Researchers concluded in this study, "The
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| | to the antigen as well as the viral
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| therapeutic challenge to effectively
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| | antigen. This is very important because
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| treat chronic HBV infection
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| | the virus antigen was previously being
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| continues."Having screened lamivudine for
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| | ignored." That brings us back to why
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| use in Hepatitis B at Glaxo's research
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| | lamivudine had limited success. The
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| lab at the University of Alberta, Dr.
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| | immune systems of some HBV carriers
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| Tyrrell was able to observe the immune
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| | failed to recognize the viral infection
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| response of various HBV patients. "What
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| | as a threat to the body. Tyrell's ViRexx
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| really got me interested in doing more
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| | Medical research team hopes the body's
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| work in this area was that we noticed
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| | immune system sees the threat, thus
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| patients, who have an immune response to
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| | stimulating the immune system, and
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| the virus and take lamivudine, will have
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| | breaking tolerance. It appears Dr. Tyrell
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| a better sustained response rate,"
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| | may soon find out whether or not the
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| Tyrrell explained. "A patient with
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| | questions he asked will bring the answers
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| elevated liver transaminases taking
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| | he hoped for.END OF PART ONEJames Finch
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| lamivudine had a higher probability of a
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| | contributes to and other publications.
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| sustained viral response," Tyrrell said
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| | Visit to read all of his articles. Write
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| with excitement in his voice. "In a
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| | to James Finch at Visit to find out
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| patient with normal liver enzymes, who
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| | more about the Chimigen(TM) platform.
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| gets lamivudine, the virus will go down,
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