One of the biggest concerns about blood transfusions is what might lurk in the blood – viruses, bacteria, parasites or even potentially dangerous white blood cells. Intercept, a pathogen inactivation system approved by the FDA last December, allays much of that concern by essentially castrating almost anything in the blood that uses DNA or RNA to replicate (which, on planet Earth at least, is everything we need to worry about). A handful of viruses and bacterial spores can escape the system, but clinical trials and other studies have shown its effectiveness with HIV, hepatitis B and C viruses, West Nile virus, gram-negative and gram-positive bacteria and, importantly, tropical diseases such as dengue fever and chikungunya.
The Red Cross started using the system in Puerto Rico for donated platelets last week in the midst of a chikungunya outbreak that’s been sickening and killing residents for months. Though the Red Cross, hospitals and other medical providers test blood donations, no currently available blood tests can detect chikungunya or dengue fever, both tropical diseases that have become increasingly prevalent in the U.S. and U.S. territories with global climate change. In fact, available culture testing cannot detect more than half of bacterially infected blood, according to press materials from
The confirmed transmission of chikungunya in December 2013 and the subsequent outbreak likely played a role in the FDA fast-tracking their approval of the system for platelets and plasma, which has been approved in Europe for platelets since 2002 (plasma in 2006). According Cerus, more than 20 countries in Europe, Russia and the Middle East use the system. Until now, the Puerto Rico Department of Health protocol for reducing the risk of chikungunya or dengue transmission via donated platelets has been to wait 72 hours after a donation to see if the donor develops disease symptoms before using the donation. But platelets have only a 5-day shelf life, during which the risk of bacterial contamination increases, so this protocol leaves only a brief window in which the blood can be safely used. The Red Cross in Puerto Rico had stopped doing platelet collections altogether during the outbreak and was using only imported blood supplies from the continental U.S.
Intercept’s mechanism is elegantly simple: a proprietary molecule called amotosalen HCl is added to platelets and plasma and then activated by ultraviolet light. The molecule then gets to work by basically unzipping any RNA and DNA in the sample, whether it’s in a virus, bacterium, parasite, white blood cell or any other substance. Then it crosslinks the nucleic acids – zipping back up the DNA or RNA crookedly – which prevents replication and inactivates the pathogens. For red blood cells, a different activation is used because light does not pass through hemoglobin. Instead, tweaking the pH activates a different proprietary molecule called S-303, which then does the same nucleic acid crosslinking.
The Intercept Blood System works by criss-crossing the nucleic acids, the As, Ts, Gs and Cs in the... [+]
Inactivating viruses, bacteria or parasites has obvious benefits, but inactivating white blood cells can reduce the risk of rare but usually fatal transfusion-associated graft versus host disease, in which the T cells in the donor blood attack the tissues of the recipient. Meanwhile, platelets, plasma and red blood cells do not need functional DNA or RNA to do their jobs (clotting, mending blood vessels, dissolving solutes and transporting oxygen).
The Puerto Rican Department of Health’s decision to allow Intercept as an alternative to the 72-hour donor blood quarantine marks the system’s first use in the U.S. and its territories. Meanwhile, SunCoast Blood Bank in Florida and Blood Bank of Delmarva in Delaware, which provide blood supplies to approximately 30 hospitals and healthcare facilities combined, have recently entered agreements with Cerus to use Intercept Blood System for platelets and plasma.
