Dallas,
TX (3/19/99) - Adenovirus, one of the causes of the ubiquitous common
cold, can also cause severe heart muscle damage, say researchers. The finding
offers new opportunities for diagnosis and treatment of a disease that often
afflicts young athletes in their prime.
Left ventricular dysfunction, or LVD, is a rare disease of the heart muscle.
In patients with LVD, the left ventricle- the main pump of the heart- weakens,
and the heart deteriorates. Diagnosis can be tricky and few treatments exist
other than heart transplantation. While known causes include coronary heart
disease; genetic defects; and even tissue damage from using cocaine, the cause
in many cases remains a mystery.
"LVD, is not a common disease, but it has a major impact. When you see
a high school student drop dead playing sports, LVD is one of the common causes,"
said Jeffrey A. Towbin, M.D., a researcher at Baylor College of Medicine,
Houston, TX.
Dr. Towbin, who previously had discovered an association between adenovirus
infection and LVD in children wanted to know if the same was true for adults
with the disease. Working with German researchers, he studied tissue samples
from the hearts of 94 adults with LVD of unknown origin. The researchers used
polymerase chain reaction (PCR) screening to search for viruses in the heart
muscle.
The PCR screening provided genetic evidence of adenoviruses in 12 LVD patients,
and genetic material from enteroviruses in another 12. The test uncovered
no evidence of viral infections in the hearts of any of the 14 members of
the control group.
"Adenovirus, a common cause of upper respiratory infection, must be
considered as a potential cause of heart muscle disease. For that reason,
pediatricians, family physicians and internists should take into account the
potential late-onset of cardiovascular complications that may occur after
the typical flu-like illness. Patients who feel poorly several weeks after
a flu-like illness should contact their physicians. Usually symptoms will
be fatigue or shortness of breath that continue after recovery from the respiratory
illness. A physical exam or chest X-ray can reveal heart enlargement+,"
said Towbin.
The diagnostic PCR test for adenovirus will increase the likelihood of determining
the underlying cause of heart muscle dysfunction in individual patients. The
finding could lead to new strategies to prevent or treat LVD, which leads
to disabling and eventually fatal heart failure and sudden death, he added.
A vaccine against specific adenovirus types is available. Further studies
will need to be done to determine if the vaccine is effective against the
types that cause LVD.
Adenovirus is best known as a cause of infections of the upper respiratory
tract symptoms, producing symptoms of pharyngoconjunctival fever, and pneumonia.The
adenovirus is transcribed and replicated in the nucleus of the host cell.
In the same fashion as the host cell's mRNA, the nucleic acids are modified
post-transcriptionally and moved to the cytoplasm for translation. The adenovirus
shuts down the cell's ability to move its own mRNA from the nucleus into the
cytoplasm. Only viral mRNA is moved. Therefore, after a period, only viral
mRNA is found in the cytoplasm.
More recently, genetically modified forms of adenovirus have been the vector
of choice for gene therapy studies in humans, including gene therapy of the
heart. Adenovirus is also being used in the production of live virus vaccines.
The research appears in Circulation, the Journal of the American Heart
Association.
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