Navigation Links
Study confirms early elevated HIV infection risk in some Step Study participants
Date:5/7/2012

SEATTLE A long-term follow-up analysis of participants in the Step Study, an international HIV-vaccine trial, has confirmed that certain subgroups of male study participants were at higher risk of becoming infected after receiving the experimental vaccine compared to those who received a placebo. The vaccine used in the study did not contain the HIV virus, but it did contain HIV genes which were delivered to cells using a vector that employed a type of cold virus known as adenovirus serotype 5 (Ad5).

Of the 1,836 men examined in this study, 172 became infected with HIV. Within 18 months of enrollment or one year after the last vaccination, men who had neutralizing antibodies to Ad5 or who were uncircumcised, or both, had a two- to four-fold increased risk of acquiring an HIV infection, according to findings published in the May 4 online edition issue of the Journal of Infectious Disease.

However, the study also found that the risk level waned after about 18 months to be equal to that of volunteers who received a placebo.

Why this association occurred, what the biological mechanisms were and why the risk of infection lessened with time are unknown and require more study, according to Ann Duerr, M.D., a member of the Vaccine and Infectious Disease Division of Fred Hutchinson Cancer Research Center, who led the data analysis.

"There seems to be some kind of biologic phenomena that affects infection risk," she said.

The current study indicated that self-reported risk behaviors, such as unprotected sex, did not differ significantly between the vaccine and placebo arms of the Step trial.

The research also confirmed there was no elevated risk of infection in vaccinated men who were circumcised and who were Ad 5 seronegative (men who had no neutralizing antibodies to the adenovirus vector used in the vaccine). An earlier interim analysis of the Step Study data, done after immunizations in the vaccine trial were halted in 2007, also detected this relationship between Ad5 sero-status and vaccine-associated HIV risk. Today, only men who are circumcised and Ad5 seronegative are eligible to receive experimental HIV vaccines that use the adenovirus serotype 5 as a biological delivery mechanism.

Duerr said scientists need a better understanding of what happened biologically to men who became infected, before those who are uncircumcised or seropositive for Ad 5 are enrolled in future vaccine trials in which the adenovirus serotype 5 vector is used.

Ad 5 is used as a vector because it elicits a strong immune response by CD8 T cells. These cytotoxic T lymphocytes are thought to be responsible for controlling HIV infection.

In the current study, researchers analyzed data from male Step Study participants who enrolled in a trial that provided follow-up for up to four years after they enrolled in the Step study, or until Dec. 31, 2009, whichever came first.

The Step Study enrolled 3,000 male and female volunteers in North and South America, the Caribbean and Australia between 2004 and 2007. Injections in the study were halted in September 2007 after researchers detected a lack of effectiveness by the vaccine to prevent HIV acquisition or reduce HIV viral load in infected participants, and a higher-than-expected number of HIV infections in certain subgroups of vaccinees.
'/>"/>

Contact: Dean Forbes
dforbes@fhcrc.org
206-667-2896
Fred Hutchinson Cancer Research Center
Source:Eurekalert

Related medicine news :

1. Despite Treatment, Employees with Depression Generate Higher Absentee Costs, According to Thomson Reuters Study
2. American Council on Exercise (ACE) Study Reveals Kettlebells Provide Powerful Workout in Short Amount of Time
3. TV drama can be more persuasive than news program, study finds
4. Study carried out into biological risks of eating reptiles
5. Neuroimaging study may pave way for effective Alzheimers treatments
6. Study finds racial gaps continue in heart disease awareness
7. Luth Researchs IndicatorEDG(TM) Study Finds Americans Hopes of Achieving Their Dreams Are Fading
8. First blinded study of venous insufficiency prevalence in MS shows promising results
9. Soothing infants with food focus of childhood obesity study
10. People with anxiety disorder less able to regulate response to negative emotions, study shows
11. American Heart Association Rapid Access Journal Report: Study Finds Racial Gaps Continue in Heart Disease Awareness, Low Knowledge of Heart Attack Warning Signs Among Women
Post Your Comments:
*Name:
*Comment:
*Email:
(Date:6/26/2016)... ... 2016 , ... Quality metrics are proliferating in cancer care, and are derived ... eye of the beholder, according to experts who offered insights and commentary in the ... Care. For the full issue, click here . , For the American Society ...
(Date:6/26/2016)... , ... June 26, 2016 , ... Pixel Film Studios ... X. , "Film editors can give their videos a whole new perspective by using ... - CEO of Pixel Film Studios. , ProSlice Levels contains over 30 Different ...
(Date:6/26/2016)... ... 2016 , ... Brent Kasmer, a legally blind and certified personal trainer is helping to develop ... The fitness app plans to fix the two major problems leading the fitness industry today:, ... all type program , They don’t eliminate all the reasons people quit their ...
(Date:6/25/2016)... (PRWEB) , ... June 25, 2016 , ... ... health policy issues and applications at AcademyHealth’s Annual Research Meeting June 26-28, 2016, ... work on several important health care topics including advance care planning, healthcare costs ...
(Date:6/25/2016)... ... June 25, 2016 , ... The temporary closing of Bruton Memorial Library on June ... , brings up a new, often overlooked aspect of head lice: the parasite’s ability to ... is not a common occurrence, but a necessary one in the event that lice have ...
Breaking Medicine News(10 mins):
(Date:6/23/2016)... 2016 Research and Markets has announced ... report to their offering. ... a favourable commercial environment for MedImmune to enter. The US ... will serve to drive considerable growth for effective anti-influenza medications. ... cap sales considerably, but development is still in its infancy. ...
(Date:6/23/2016)... 23, 2016  Astellas today announced the establishment of Astellas Farma Colombia (AFC), a new affiliate with operations headquartered ... Latin America . ... ... ... ...
(Date:6/23/2016)... -- Research and Markets has announced the ... (United States, China, Japan, Brazil, United Kingdom, Germany, France, ... Surgical Procedure Volumes: ... provides surgical procedure volume data in a geographic context. ... analysis of growth drivers and inhibitors, including world population ...
Breaking Medicine Technology: