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| Dr. Robert Lanford leads SFBR's research
programs on hepatitis viruses. |
Hepatitis B
The vaccine currently used to protect humans was developed
using the chimpanzee model. This vaccine, developed by
Merck and tested for efficacy and safety by SFBR,
is now administered to children so that current and future
generations can grow up free from HBV infection. Hepatitis
B is a disease with potentially devastating effects, and it
is the world's leading cause of liver cancer.
Hepatitis C
The hepatitis C research program at
SFBR has offered the first evidence that an effective vaccine
against hepatitis C should be possible. Hepatitis C virus (HCV) is estimated to infect
3 percent of the population worldwide and more than 2 percent
of the U.S. population. The leading cause of liver failure
and liver transplantation in the United States, HCV infection
also accounts for approximately 25 percent of all hepatocellular
carcinomas. The extraordinary genetic and antigenic diversity
of HCV virus strains has been thought to make development
of a successful vaccine impossible. However, SFBR researchers
recently demonstrated that chimpanzees that had previously
cleared infection with one strain of HCV showed protective
immunity when challenged with other strains of the virus.
This offers hope that a successful vaccine against all strains
of hepatitis C could be on the horizon.
AIDS
Performed the first transmission of HIV to a chimpanzee.
In collaboration with scientists at the National Institutes
of Health, HIV-contaminated blood was used to infect a chimpanzee,
creating an animal model to study the disease and potential
therapies, including vaccines. Although chimpanzees may become
infected with HIV, they do not progress to clinical disease
as humans do. The development of this animal model has provided
a valuable tool for AIDS research, allowing the following research
successes at SFBR:
SFBR researchers have tested more than 25 vaccine candidates
for HIV. Two of these vaccines protected chimpanzees
from HIV infection and advanced to clinical trials with
human subjects, with one going on to large-scale Phase III
clinical trials. Other vaccine candidates are currently
being tested in the chimpanzee model as scientists continue
their hopeful search for a protective vaccine for HIV and
AIDS.
A new antibody against HIV was shown to prevent infection
in chimpanzees treated with the antibody either one hour
before or one hour after exposure to HIV. Development
of this technology will provide a new method for preventing
HIV infection in health care workers accidentally exposed
to HIV-contaminated blood. It also could provide an adjunct
therapy for the possible prevention of mother-to-child transmission
of the disease.
Herpes B
Scientists at SFBR helped develop methods to rapidly
diagnose and treat herpes B virus infections, which are
transmitted from Asian monkeys to humans and have a high fatality
rate for humans. At particular risk are researchers who handle
rhesus monkeys and other macaques or those who work with these
animals' tissues.
Respiratory Syncytial Disease (RSV)
Developed a new animal model for respiratory syncytial
disease (RSV) using newborn baboons. This will aid in
the development of a vaccine that will be given to pregnant
females so that babies will be born with sufficient antibodies
against RSV to prevent infection until their own immune system
is mature enough to provide protection. RSV is associated
with an estimated 90,000 hospitalizations and 4,500 deaths
from lower respiratory tract disease annually. The virus also
causes repeated infections throughout life.
Chagas Disease
Chagas disease is a parasitic disease in humans that causes
several debilitating conditions, including heart failure and
digestive disorders associated with the enlargement of the
esophagus or colon. It is endemic in 21 countries, with an
estimated 18 million persons infected and 100 million at
risk of infection. Chagas disease is of increasing concern in the
United States since both the vector and parasite are common
throughout much of the country, including Texas.
SFBR scientists have characterized several families of
500 people or more in Brazil who have high
rates of Chagas disease. With NIH funding, scientists
are studying this population to identify potential genetic
mechanisms that will explain why only 65 percent of the exposed
population becomes infected and why 30 percent of infected
individuals develop clinical disease.
Helminthic Infections
Working with 2,000 members of a single
family in Nepal, SFBR scientists have localized two genes
that contribute to susceptibility to roundworm infection.
This is the first evidence establishing that human host
genes influence susceptibility to an intestinal worm infection.
Since roundworm infection has always been thought to be
simply a function of poor environmental quality, the identification
of genetic influences on the disease represents a major
change in the understanding of risk factors for intestinal
worm infections.
Equine Encephalitis
Scientists at SFBR isolated a new virus that causes equine
encephalitis and is present in Mexican states that border
Texas. This mosquito-borne virus is a new threat to
livestock and humans living in Texas.
Dengue Hemorrhagic Fever
SFBR researchers identified structural differences in
the DNA of dengue viruses that determine the severity of
dengue hemorrhagic fever in humans. This will aid in
the development of prevention strategies and treatment methods
for dengue fever, which is spread by mosquitoes to humans.
Infection with dengue viruses produces a spectrum of clinical
illness that can result in fatal hemorrhagic disease.
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