Mikovits was keenly aware of two well-documented immune system abnormalities in CFS. One was a stark deficiency in the total number of natural killer cells, which seek out and destroy viruses and cancer cells, and a reduction in the killing power of the natural killer cells that remained.
A second abnormality had to do with elevated levels of RNase L, an enzyme that provides immunological defense against viruses and cancer. “Given that the job of RNase L was to chew up RNA viruses, we hypothesized the possibility of a novel RNA virus in our patients,” Mikovits says. (RNA viruses use ribonucleic acid as their genetic material; examples include SARS, polio, and retroviruses like HIV.)
Patients with aggressive prostate cancer, the second-leading cause of cancer deaths among men, had RNase L abnormalities too. In 2002, Robert Silverman, an RNase L expert at the Cleveland Clinic, discovered that a mutation in the RNase L gene was frequently present in men prone to early onset of the disease.
Silverman, too, suspected an RNA virus might be the infectious cause of aggressive cancers in relatively young men. And he had some preliminary evidence: When he added DNA from malignant prostate tissue cells to a microarray, a novel retrovirus emerged. Further analysis showed that the retrovirus was a gammaretrovirus closely linked to MLVs found in mice, though analysis revealed its genome to be slightly—less than 3 percent—different.
Silverman’s group at the Cleveland Clinic and collaborators Joe DeRisi and Don Ganem in San Francisco reported their discovery of a new, apparently human retrovirus in PloS Pathology in March 2006; the researchers added the word xenotropic to the name to indicate that the virus, although carried from generation to generation in the mouse genome, caused disease only in other animals. At the time, the paper attracted little interest from the scientific community.
In January 2009, Mikovits and Ruscetti—by then also hot on the trail of the enigmatic virus—met with Silverman in San Diego, where he had been invited to speak. Over lunch, Mikovits laid out her preliminary data. Using polymerase chain reaction (PCR) technology to greatly amplify what began as tiny amounts of the virus, she had found evidence for the novel pathogen in CFS patients as well. “We all agreed it was worth following up,” Mikovits recalls.
Silverman and Ruscetti signed a confidentiality agreement with the Whittemore Peterson Institute and became Mikovits’s collaborators. Their paper, “Detection of an Infectious Retrovirus, XMRV, in Blood Cells of Patients with Chronic Fatigue Syndrome,” appeared in the online edition of Science on October 8, 2009. Two MLV experts, one from Britain and another from the United States, extolled the importance of the work in an accompanying editorial, writing, “If these figures are borne out in larger studies, it would mean that perhaps 10 million people in the United States and hundreds of millions worldwide are infected.”
By November 2009, Stuart Le Grice, head of an influential NCI division called the Center of Excellence in HIV/AIDS and Cancer Virology and the person who had convened the NIH meeting the previous summer, had 10 HIV scientists working full time on XMRV. “It’s very interesting to be in the middle of a situation like this,” Le Grice commented at the time. “I worked with Hoffmann–La Roche for seven years in Switzerland in the first days of HIV, and the action plan that we put together at Roche is the same plan that we put together here.”
Mikovits, for her part, took pains to tell members of the lay press and other scientists that the virus had not been proved to cause CFS, merely that it was “associated” with the disease. But in private, contemplative moments that fall, the researcher indicated she felt confident that the long-enduring CFS puzzle was likely solved; her real interest going forward was in developing treatment for those who were suffering.
WHILE SCIENTISTS AT THE NCI WERE repurposing laboratory space to study XMRV, William Reeves, the researcher in charge of CFS for 18 years at the CDC (he died last August) and a longtime proponent of the psychiatric explanation for the disease, sounded a sour note, telling The New York Times, “If we validate it, great. My expectation is that we will not.”
For many researchers who had followed the CDC’s desultory history in CFS over the years, Reeves’s comments aroused concern. Twenty years earlier, another scientist, immunologist Elaine DeFreitas of the Wistar Institute in Philadelphia, had discovered retroviral gene sequences in CFS sufferers.
The agency failed to replicate her findings after a series of lab mishaps and a wholesale departure from DeFreitas’s protocol for finding the virus. Afterward, the CDC reverted to its years-long claim that CFS was lacking in biological abnormalities and its assertion to doctors that performing any but the most standard tests was a waste of money.
Academic research into the cause of the disease went into a 20-year stall, punctuated in 2006 by a press conference in which Reeves and the CDC’s director at the time, Julie Gerberding, announced what they portrayed as a breakthrough discovery: CFS was caused by a genetic predisposition to difficulty responding to stress.
In late 2009 at CDC headquarters in Atlanta, a virologist in the agency’s retroviral branch, William Switzer, was attempting to replicate the XMRV finding in CFS. In an ironic twist, Switzer was working under the direct supervision of Walid Heneine, the very scientist who had failed to replicate DeFreitas’s work 20 years before. So far, the agency had found XMRV in 2 out of 162 men with prostate cancer but was having zero luck finding it in agency-selected CFS patients.
By the start of 2010, it seemed as if the Science article had launched a cottage industry of researchers on two continents who were unable to find XMRV in CFS patients. The first negative results appeared in January when a group from Imperial College London published an article in PLoS ONE saying they had failed to find the virus in 186 CFS patients using PCR technology.
In February, a Dutch group at Radboud University followed with another negative PCR study, reporting in the British Medical Journal that it had been unable to find XMRV in 32 patients or 43 healthy controls. Back in the United States the following summer, the CDC reported in the journal Retrovirology its inability to find XMRV in either CFS patients or controls.
Despite the skepticism emerging in Europe and the U.S., events were quietly unfolding in a laboratory at the FDA in Rockville, Maryland, that would put Mikovits’s critics back on the defensive.