Something in the Blood

This is the third post in The Scope blog series “HIV: A Scientific Discovery,” a collection of pieces that explore the major scientific milestones in the discovery of the HIV virus.

The common thread had been found: an impaired immune system, weakened to the point that it could no longer protect its human home from the hordes of opportunistic infections that, in just a few months, had claimed the lives of over a hundred young American men. Although still largely unexplained, the Kaposi’s Sarcoma (KS) and Pneumocystis carinii Pneumonia (PCP) outbreaks’ most prominent feature had nevertheless been characterized at last. The CDC, eager to put a name to the condition, announced in June of 1982 that the new disease would be termed Gay-Related Immune Deficiency (GRID).

The name did not stick for long, however. The next month, the CDC reported a GRID-like illness in a group of Haitians throughout the US. The patients had all of the symptoms of GRID, yet there was nothing “Gay-Related” about their disease. A condition uncannily resembling GRID had also been diagnosed in heterosexual females who had been sexual partners with men later diagnosed with the disease. “GRID,” it seemed, was not as picky as they thought. The condition’s previously exclusive manifestation in homosexual men had given hope to doctors and public health officials that they had seen the true face of the illness. Yet it was just another mask.

With wise caution, the CDC renamed the disease “Acquired Immune Deficiency Syndrome” (AIDS) in September. Though they knew it was somehow “acquired,” they would not find out how until December of that year, when a 20-month old infant was admitted to a San Francisco hospital after showing signs of AIDS (imagine the shock if GRID had not been renamed). Although the child’s immune deficiency could not be explained by any prior health history, doctors noticed on the child’s medical chart that the boy had received multiple blood transfusions at birth in order to treat a blood disease known as neonatal jaundice. One of these transfusions came from a young man who had been recently diagnosed with AIDS in the months following the blood donation. Doctors were horrified. Could the nation’s blood bank be contaminated with AIDS?

Even if it were, there was nothing public health officials could do. What would they filter out from the blood? What would they even look for? AIDS was a condition, not a molecule. What they did know now, though, was that blood was key. This finding led epidemiologists to publish an editorial the following summer in The Journal of the National Cancer Institute, at last providing a plausible explanation for an outbreak that had by then spread to 1200 people: a blood-transmitted infectious agent. Only something infectious could cause such a localized outbreak among a group of people who had come into direct contact with others’ blood, whether through sexual intercourse, needle sharing in drug abuse, or a seemingly benign blood transfusion. Among all the possible infectious agents, viruses had been prime suspects for the outbreak ever since the KS diagnoses of 1981, and now they were dragged into the limelight of scientific scrutiny.

But why a virus, and not a parasite, bacterium, or other infectious agent? The evidence lay in well-characterized viruses that had similarly sophisticated strategies of infection, chief among them being the Hepatitis B Virus (HBV) and Human T-Cell Leukemia Virus (HTLV). HBV was known to also preferentially target homosexual men, yet it had never before been characterized by suppression of the immune system, the signature of AIDS. HTLV, on the other hand, while not as well studied as HBV, was associated with many of the symptoms of AIDS.

The virus preferentially attacked T-cells and effected widespread dysfunction of cellular immunity, a convincing explanation for the immune impairment seen in AIDS patients. HTLV had rarely been seen in the US before 1983, but its recent emergence in Japan put American doctors on edge. The accumulation of two years of frantic searching and diligent research pointed directly at HTLV as the agent of destruction, if not an entirely new virus. Doctors had finally arrived at a convincing hypothesis; it was now up to the scientists to prove it.

Coming up next week: The hunt for “the AIDS virus” begins.

Kevin Wang is a junior in Ezra Stiles College. Contact him at kevin.wang@yale.edu.

(Featured Image courtesy of Pixabay.)