标题: 乙肝杂志回顾 2013年12月1日Christine M. Kukka [打印本页] 作者: StephenW 时间: 2013-12-2 15:45 标题: 乙肝杂志回顾 2013年12月1日Christine M. Kukka
Studies Find Hepatitis B Virus Can Mutate and Infect Even Immunized People
A growing number of studies are finding that the hepatitis B virus (HBV) is so adept at mutating that in some cases it is able to infect people who have been immunized against hepatitis B.
The hepatitis B vaccine contains only one particle (antigen) of the virus—the hepatitis B surface antigen (HBsAg)—which makes up the outer layer of the virus. When immunized with this antigen, the body's immune system creates the hepatitis B surface antibody to specifically target and eradicate HBsAg if a person comes in contact with the virus. To date, the vaccine has effectively protected millions against hepatitis B.
However, researchers are finding some people who were immunized and then exposed to the virus are now infected with HBV that is able to replicate without HBsAg. Scientists say these vaccinated people have "occult" or a "vaccine escape" version of the infection. They have HBV DNA in their bodies, but they test negative for normal HBsAg.
A new study published in the November issue of the Journal of Virology finds that the number of vaccinated Chinese children with mutated HBV has increased from 6.5% in 1992 to 15% in 2005.(1) And, as these vaccinated children age and become adults, the rate of mutations increases. Researchers also fear these mutated virus may cause more severe liver disease in patients than regular HBV.
"The vaccine has been successful in protecting millions of children from HBV, but there is concern that use of the vaccine puts selective pressure on the virus to develop 'breakout' mutations that could render the vaccine less effective," wrote M. J. Friedrich in an editorial citing the study, entitled, "Hepatitis B vaccination spurs virus mutation rise," in the November issue of the Journal of the American Medical Association.(2)
In the investigation, researchers from the U.S. and China compared blood samples taken from vaccinated children and unvaccinated adults before and after universal HBV immunization began in China in 1992. "They found that the prevalence of HBV mutants in children increased from 6.5% in 1992 to almost 15% in 2005, whereas in the adults, little difference was seen in HBV mutation prevalence from 1992 to 2005—as would be expected because the adults did not receive vaccines.
"Although the vaccine remains effective, this study indicates that HBV mutations should be monitored so that additional vaccination strategies can be implemented when necessary," Friedrich cautioned.
In another study, published in the November issue of the Journal of Viral Hepatitis, researchers compared outcomes in babies born to HBV-infected mothers who were given only the vaccine or a combination of the vaccine and HBIG, which is composed of hepatitis B surface antibodies derived from humans. They found occult hepatitis B, with HBsAg mutations, in 42% of 222 babies two years after their births.(3) The occult infection rate was higher in infants treated with both the vaccine and HBIG, and whose mothers had high rates of HBV DNA when they were born.
Hepatitis B Patients Appear to Be At Risk of Other Diseases
Several new studies report that people with chronic hepatitis B appear to be at higher risk of heart disease, eye problems and fibromyalgia.
Abnormally High Rates of Heart Disease Found in Hepatitis B Patients: Japanese researchers screened 47 hepatitis B patients, who had no overt signs of cardiac problems, for heart disease using a variety of tests.
Myocardial perfusion defects (injury to heart muscle and restriction of blood flow) were found in 47% of the hepatitis B patients (far higher than in an uninfected control group) and abnormal electrocardiography results were found in 9% of the patients, according, according to a report in the November issue of the Journal of Gastroenterology and Hepatology.
The severity of the heart disease was then monitored during and after interferon treatment in 10 patients—and researchers found that heart disease markers declined in those patients who responded well to the interferon treatment.
"Myocardial perfusion defects were found in 47% of the patients with chronic hepatitis B, and improved along with (viral load) reduction with interferon administration," they reported. (1)
Higher risk of macular degeneration reported in older, HBV-infected patients:
An article in the November issue of the journal of Investigative Ophthalmology and Visual Science reports that hepatitis B infection, in addition to other risk factors, increases risk of macular degeneration, which is a major cause of partial-blindness in people 50 and older.
The study surveyed 7,899 Koreans age 40 and older. The overall rate of early-onset age-related macular degeneration—which is a major cause of partial-blindness in people 50 and older—was estimated at 6.7% and that of late macular degeneration at 0.7%.
Significant risk factors for macular degeneration, according to researchers, included older age, high cholesterol, high blood pressure, and HBV infection.(2)
Fibromyalgia syndrome found in 22% of hepatitis B patients in small study: A Turkish study has found that 22% of 77 hepatitis B patients suffered from fibromyalgia—a syndrome with widespread fatigue, muscle pain, morning stiffness and sleep disturbance.
It made no difference if the patients had "active" hepatitis B with liver damage or high viral load. The syndrome affected both types of chronic hepatitis B patients, according to the report published in the September issue of the International Journal of Clinical and Experimental Medicine.
"Recognition and management of fibromyalgia in HBsAg-positive patients will aid in improvement of quality-of-life," researchers wrote. "We fully accept that our preliminary results require confirmation in (larger) studies... More work is needed to ... understand the role played by, and the relevance of, infections (including HBV) in fibromyalgia syndrome pathogenesis."(3)