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March 2004
NIAID Research on Severe Acute Respiratory Syndrome (SARS)
What is SARS?
NIAID Research on SARS and Coronaviruses
Understanding the virus and how it spreads
Studying SARS in the clinic
Developing drug treatments
Developing diagnostic tests
Developing vaccines
Providing resources to researchers
What is SARS?
- Severe acute respiratory syndrome (SARS) is a new infectious disease
first identified in humans in early 2003.
- SARS is caused by a newly described coronavirus, called SARS-associated
coronavirus (SARS-CoV). Previously identified human coronaviruses
(named for their spiky, crown-like appearance) were known to cause
only mild respiratory infections.
- SARS typically begins with flu-like symptoms, including high fever
that may be accompanied by headache and muscle aches, cough, and shortness
of breath. Up to 20 percent of infected people may develop diarrhea.
Most SARS patients subsequently develop pneumonia. In the 2003 outbreak,
there were more than 8,000 probable cases of SARS and 774 deaths (approximately
9 percent mortality), according to the World Health Organization.
Eight confirmed cases were identified in the United States, with no
deaths. For current information about SARS, visit the Centers for
Disease Control and Prevention (CDC) Web site at http://www.cdc.gov/ncidod/sars/.
- The virus spreads primarily by close human contact. SARS-CoV-containing
droplets can be released into the air when an infected person coughs
or sneezes. Some specific medical procedures performed on SARS patients
also can release virus-containing droplets into the air. Touching
a SARS-CoV-infected surface and subsequently touching the eyes, nose,
or mouth may also lead to infection.
- Intensive and supportive medical care is the primary therapy, as
no specific treatment has yet been shown to consistently improve the
outcome of the ill person.
NIAID Research on SARS and Coronaviruses
The prompt recognition that SARS is caused by a new type of coronavirus
is a tribute to the dedication of and collaboration by the world's medical
researchers and public health experts. Much more research is needed, however,
to develop ways to identify, treat, and prevent this deadly illness. NIAID
scientists, grantees, and industry partners are working to better understand
the different aspects of SARS and the virus that causes it. Below are
some recent accomplishments and goals for future efforts.
Understanding the virus and how it spreads
- Using high-powered microscopes, blood tests, and other standard
laboratory techniques, NIAID-supported scientists in Hong Kong were
the first to show that SARS was caused by a virus. Within a few days,
these scientists and others from the CDC were the first to show that
the virus was a new and deadly type of coronavirus. These efforts
subsequently sparked worldwide efforts to rapidly develop SARS-CoV
diagnostic tests, drugs, and vaccines.
- The genetic material, RNA, contained in the SARS-CoV is very difficult
to manipulate in the lab. NIAID-funded researchers generated a form
of SARS-CoV that is easier to work with. Researchers will be able
to use it to study the structure and function of viral proteins, and
use the information to develop vaccine candidates.
- An ongoing NIAID-funded program for conducting influenza surveillance
in the live bird markets of Hong Kong was expanded to search for animal
carriers of SARS-CoV. Researchers traveled to live animal markets
in China and determined that some of the samples taken from two animals,
the palm civet and the raccoon-dog, were positive for SARS-CoV. These
results were the first report of isolation of a SARS-like CoV from
animals. Although it is not known if these animals are a natural reservoir
for SARS-CoV, live animal markets provide effective opportunities
for the spread of animal viruses directly to humans.
- In the area of basic immunological research, NIAID is supporting
work to determine how the immune system responds to SARS-CoV and if
there are human genetic variations that affect how susceptible an
individual is to SARS.
- NIAID is supporting analyses of genes from human and animal coronaviruses,
including many strains taken from SARS patients. This work could lead
to a better understanding of where the virus came from and how it
causes disease, including the immune system response.
- NIAID is encouraging grant applications on the immunopathology of
SARS, including studies on inflammation and airway hypersensitivity,
and the ways in which SARS-CoV may evade destruction by immune system
cells.
- NIAID scientists have developed a mouse model of SARS, which will
allow the study of both the course of SARS infection and potential
vaccines against the disease. This model will also be used by an NIAID
contractor to evaluate the safety and efficacy of experimental therapies.
Studying SARS in the clinic
- NIAID has developed a project to study and treat SARS patients,
contacts, and health care workers. Should the disease return, these
clinical trials would take place at the NIH Clinical Center and would
include researching the disease as well as evaluating antiviral and
immune-based therapies.
- NIAID, using its Collaborative Antiviral Study Group network of
clinical trial sites, is taking the lead in a collaborative effort
with the National Heart, Lung and Blood Institute of the NIH, the
CDC, and academic and clinical investigators from the United States
and Canada to study experimental SARS therapies. One of the experimental
drugs to be evaluated for efficacy is alpha interferon, a drug already
approved by the FDA for the treatment of hepatitis B and C infections.
Developing drug treatments
- NIAID is participating in a project to screen up to 100,000 antiviral
drugs and other compounds for activity against SARS-CoV. While several
compounds have shown antiviral activity, only alpha interferon is
suitable for immediate clinical evaluation. Several compounds that
act by inhibiting the coronavirus cysteine protease enzyme showed
a dramatic amount of antiviral activity. These compounds are undergoing
preclinical safety evaluations to allow selection of a single candidate
for clinical study. Experimental compounds are provided by large and
small pharmaceutical firms, foreign and domestic academic scientists,
and members of the lay community.
- As more is learned about the mechanisms of SARS-CoV infection, it
will become possible to design drugs specifically aimed at its weak
points. NIAID-supported researchers are engaged in this rational drug
design. One such project is developing an "entry inhibitor" that prevents
SARS-CoV from infecting human cells.
- In 2003, NIAID awarded a contract to develop humanized antibodies
against SARS-CoV. It is hoped that one of these antibodies could be
used to prevent infection from gaining hold in health care workers
and others who are exposed to SARS patients.
Developing diagnostic tests
Because the symptoms of SARS are similar to those of influenza, clinicians
must have fast, accurate tests to identify and, if necessary, isolate
people with SARS. NIAID-supported scientists in Hong Kong developed
a test that is able to detect the virus in respiratory aspirates (material
taken from the lungs and bronchial passages) and in fecal samples. Research
is continuing to improve the accuracy of this test.
Developing vaccines
- Since it is not known which type of vaccine will be most effective
against the SARS-CoV, NIAID scientists and grantees are pursuing several
parallel approaches in the search for a vaccine.
- In 2003, NIAID awarded contracts to Baxter Healthcare and Aventis
Pasteur to produce experimental inactivated whole virus SARS vaccines,
and awarded a contract to Protein Sciences Corporation to produce
a recombinant subunit vaccine. Once these experimental vaccines are
ready, NIAID plans to test them in clinical trials conducted by its
Vaccine Testing and Evaluation Units.
- Scientists at NIAID's Vaccine Research Center in Bethesda, MD, have
developed an experimental SARS vaccine that prevents the SARS-CoV from replicating
in laboratory mice. They are seeking Food and Drug Administration approval to begin
early stage safety and immunology studies in people. For more details, see this
March 31, 2004, NIAID press release: http://www.niaid.nih.gov/newsroom/releases/sarsvax.htm.
- Through a grant to China's Center for Disease Control, NIAID plans
to help support the development of several separate vaccine programs,
including a protein vaccine made from select SARS-CoV proteins and
a recombinant protein vaccine.
- Scientists in NIAID's Laboratory of Infectious Diseases have developed a
mouse model for replication of SARS-CoV. They have also demonstrated that antibodies
produced by the mice block replication of SARS-CoV. These findings, described in a March
12, 2004, press release (http://www.niaid.nih.gov/newsroom/releases/sarsmouse2.htm), will
help researchers working on SARS vaccines. NIAID scientists continue to work on other
animal models, including rodents and non-human primates, to evaluate vaccine candidates
and strategies for immunotherapy.
- NIAID and foreign scientists are collaborating to develop and test
a variety of vaccines including standard killed virus vaccines and
molecularly designed vaccines, some of which can be administered intranasally.
Providing resources to researchers
- To help the world's research community develop an agenda leading
to effective control measures for SARS, NIAID convened an international
meeting of experts in May 2003. (http://www.niaid.nih.gov/sars_meeting.htm)
- Soon after the genetic code for SARS-CoV was determined, NIAID provided
interested researchers with free SARS "gene chips" embedded with a
reference strain of the virus. With the chip, researchers can rapidly
detect genetic variations among SARS strains and could eventually
determine which strains are the most dangerous as well as gaining
other information useful in developing antiviral drugs. (http://www.niaid.nih.gov/newsroom/releases/SARSChip.htm)
- NIAID has also developed synthetic fragments of key SARS-CoV proteins
that are available to SARS researchers. These protein fragments can
be used to help understand the immune response to the SARS-CoV.
- NIAID is working to establish a SARS-CoV research reagent repository.
Scientists throughout the world performing basic SARS research or
testing candidate vaccines and drugs against SARS-CoV can access them
as these reagents become available.
NIAID is a component of the National Institutes of Health (NIH),
an agency of the U.S. Department of Health and Human Services. NIAID
supports basic and applied research to prevent, diagnose and treat infectious
diseases such as HIV/AIDS and other sexually transmitted infections,
influenza, tuberculosis, malaria and illness from potential agents of
bioterrorism. NIAID also supports research on transplantation and immune-related
illnesses, including autoimmune disorders, asthma and allergies.
Press releases, fact sheets and other NIAID-related
materials are available on the NIAID Web site at http://www.niaid.nih.gov.
Prepared by:
Office of Communications and Public Liaison
National Institute of Allergy and Infectious Diseases
National Institutes of Health
Bethesda, MD 20892
U.S. Department of Health and Human Services
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Last Updated April 1, 2004 (ere)
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