MGH study examines impact of infection with both HIV and hepatitis C virus

December 11, 2006

Although many individuals infected with the hepatitis C virus (HCV) are naturally able to control levels of the virus with their immune systems, those who also become infected with HIV, the virus that causes AIDS, may lose that ability. In a report in the December issue of PLOS Medicine, a group of researchers from the Partners AIDS Research Center at Massachusetts General Hospital (PARC-MGH) report one of the first studies of how HIV infection impacts immune system functions involved with HCV control. Their findings suggest that beginning antiretroviral therapy earlier than is generally recommended may help preserve HCV control in patients infected with both viruses.

"The global burden on health of chronic viral infections is immense, and HCV and HIV are chief among culprit viruses," says Arthur Kim, MD, of PARC-MGH, co-first author of the PLOS Medicine report. "Due to shared routes of transmission, infection with both viruses is common. Unfortunately, HCV behaves as an opportunistic infection in the presence of HIV and is becoming a leading cause of illness and death in persons with HIV."

In order to examine immune system factors associated with spontaneous control of HCV and how that control is altered by HIV infection, the researchers enrolled four groups of participants: 60 were infected with both viruses, and half of those had low HCV levels upon entering the study. The other two groups of 17 participants were infected with HCV only, with one group successfully controlling viral levels. Spontaneous HCV control is known to rely on the activity of CD4 helper T cells specifically targeted against the virus, and destruction of CD4 cells by HIV underlies the immune deficiency that characterizes AIDS. Therefore the researchers measured participants' T cell response to HCV at the outset of the study and at two- to six-month intervals during the study period.

The results showed that those individuals able to maintain low HCV levels in spite of HIV coinfection had stronger virus-specific responses for both CD4 T cells and the CD8 "killer" T cells than did those with elevated HCV counts. Not surprisingly, participants infected only with HCV had even more powerful antiviral T cell responses. About a quarter of those infected with both viruses who originally controlled HCV levels lost control during the two-and-a half-year study period, and their increased virus levels corresponded with an overall drop in CD4 T cells. None of the viral controllers who were infected with HCV alone had any increase in viral levels during the study period. Loss of protective responses and susceptibility to recurrent HCV infection may help to explain the higher rates of persistent HCV observed in subjects who are HIV/HCV coinfected, compared to those with HCV alone.

In analyzing factors that might be associated with the loss of HCV control in those infected with both viruses, the researchers made a surprising discovery. The factor most powerfully associated with maintaining HCV control was not the CD4 T cell count upon entering the study but the lowest previously recorded or 'nadir' CD4 count. That finding suggests that, for individuals infected with both viruses, beginning antiretroviral treatment before CD4 levels drop too low to maintain HCV responses may be desirable.

The researchers also found that, among those whose HCV levels rose, individuals who maintained some T cell responses had lower viral levels than did those with little or no T cell response. This suggests that the immune system retains a level of secondary immunity against HCV - the kind of 'memory' response against a previously encountered pathogen seen in many infections.

"Currently a nationwide trial is recruiting people for a study examining whether earlier treatment of HIV will improve hepatitis C treatment outcomes," Kim says. "Part of this study will investigate how earlier treatment may affect immune responses. It also will be important to follow the impact of loss of HCV control on liver disease, since this will probably have important consequences for patients with HIV." Kim is an instructor in Medicine at Harvard Medical School.
-end-
Bruce Walker, MD, director of the Partners AIDS Research Center at MGH and a Howard Hughes Medical Institute (HHMI) investigator is senior author of the PLOS Medicine report, and Julian Schulze zur Wiesch, MD, of PARC-MGH and HHMI is co-first author. The study's co-authors are Thomas Kuntzen, MD, Joerg Timm, Daniel Kaufmann, MD, Jared Duncan, Andrea Jones, Benjamin Davis, MD, Rajesh Gandhi, MD, Gregory Robbins, MD, Todd Allen, PhD, and Georg Lauer, MD, of PARC-MGH, Raymond Chung, MD, MGH Gastroenterology; and Alysse Wurcel, Lemuel Shattuck Hospital, Boston. The study was supported by grants from the National Institutes of Health, the Campbell Foundation, the American Liver Foundation, the German Academic Exchange Service, Doris Duke Charitable Foundation and the Howard Hughes Medical Institute.

Massachusetts General Hospital, established in 1811, is the original and largest teaching hospital of Harvard Medical School. The MGH conducts the largest hospital-based research program in the United States, with an annual research budget of nearly $500 million and major research centers in AIDS, cardiovascular research, cancer, computational and integrative biology, cutaneous biology, human genetics, medical imaging, neurodegenerative disorders, regenerative medicine, transplantation biology and photomedicine. MGH and Brigham and Women's Hospital are founding members of Partners HealthCare System, a Boston-based integrated health care delivery system.

Massachusetts General Hospital

Related HIV Articles from Brightsurf:

BEAT-HIV Delaney collaboratory issues recommendations measuring persistent HIV reservoirs
Spearheaded by Wistar scientists, top worldwide HIV researchers from the BEAT-HIV Martin Delaney Collaboratory to Cure HIV-1 Infection by Combination Immunotherapy (BEAT-HIV Collaboratory) compiled the first comprehensive set of recommendations on how to best measure the size of persistent HIV reservoirs during cure-directed clinical studies.

The Lancet HIV: Study suggests a second patient has been cured of HIV
A study of the second HIV patient to undergo successful stem cell transplantation from donors with a HIV-resistant gene, finds that there was no active viral infection in the patient's blood 30 months after they stopped anti-retroviral therapy, according to a case report published in The Lancet HIV journal and presented at CROI (Conference on Retroviruses and Opportunistic Infections).

Children with HIV score below HIV-negative peers in cognitive, motor function tests
Children who acquired HIV in utero or during birth or breastfeeding did not perform as well as their peers who do not have HIV on tests measuring cognitive ability, motor function and attention, according to a report published online today in Clinical Infectious Diseases.

Efforts to end the HIV epidemic must not ignore people already living with HIV
Efforts to prevent new HIV transmissions in the US must be accompanied by addressing HIV-associated comorbidities to improve the health of people already living with HIV, NIH experts assert in the third of a series of JAMA commentaries.

The Lancet HIV: Severe anti-LGBT legislations associated with lower testing and awareness of HIV in African countries
This first systematic review to investigate HIV testing, treatment and viral suppression in men who have sex with men in Africa finds that among the most recent studies (conducted after 2011) only half of men have been tested for HIV in the past 12 months.

The Lancet HIV: Tenfold increase in number of adolescents on HIV treatment in South Africa since 2010, but many still untreated
A new study of more than 700,000 one to 19-year olds being treated for HIV infection suggests a ten-fold increase in the number of adolescents aged 15 to 19 receiving HIV treatment in South Africa, according to results published in The Lancet HIV journal.

Starting HIV treatment in ERs may be key to ending HIV spread worldwide
In a follow-up study conducted in South Africa, Johns Hopkins Medicine researchers say they have evidence that hospital emergency departments (EDs) worldwide may be key strategic settings for curbing the spread of HIV infections in hard-to-reach populations if the EDs jump-start treatment and case management as well as diagnosis of the disease.

NIH HIV experts prioritize research to achieve sustained ART-free HIV remission
Achieving sustained remission of HIV without life-long antiretroviral therapy (ART) is a top HIV research priority, according to a new commentary in JAMA by experts at the National Institute of Allergy and Infectious Diseases (NIAID), part of the National Institutes of Health.

The Lancet HIV: PrEP implementation is associated with a rapid decline in new HIV infections
Study from Australia is the first to evaluate a population-level roll-out of pre-exposure prophylaxis (PrEP) in men who have sex with men.

Researchers date 'hibernating' HIV strains, advancing BC's leadership in HIV cure research
Researchers have developed a novel way for dating 'hibernating' HIV strains, in an advancement for HIV cure research.

Read More: HIV News and HIV Current Events
Brightsurf.com is a participant in the Amazon Services LLC Associates Program, an affiliate advertising program designed to provide a means for sites to earn advertising fees by advertising and linking to Amazon.com.