Private Lives: Personal essays on the news of the world and the news of our lives.  The needle penetrated my latex glove and slipped into the soft skin of my finger. It was quick and painless. I was in the animal lab of Children’s Hospital Los Angeles, buried under Sunset Boulevard. Despite the thousands of mice within, the lab was peaceful. I was alone.  In front of me, in a vented, pressurized hood, lay a small white sleeping mouse. It wore a tiny plastic mask around its nose, which pumped in anesthetic. But the drug wasn’t working well enough. I was about to inject the mouse with an unusually aggressive strain of H.I.V., taken from the spinal fluid of a young man who succumbed quickly to AIDS and made more deadly in the lab, when the mouse suddenly jerked. I stuck myself with the needle instead.  This was six years ago, the third year of my doctoral studies. I hadn’t lived in Southern California long. Los Angeles didn’t feel like my city. It still belonged to my mom. Four years earlier, only a few miles away from the lab, my mom had killed herself. When the mother you love decides to leave you, in the most final way a person can, it changes you forever. She didn’t have to die. But she did.  A suicide turns you into a meticulous researcher. I have spent hours, weeks, perhaps months of my life repeating the exact words of our last phone conversation. I have agonized over her final days, analyzed her receipts, re-enacted her last meal, worn her jewelry and even emailed her high school boyfriend. Few other deaths can lead family members to this level of detailed personal research. Every book will tell you: You can never know why. But the only thing that’s important is understanding why. The path is a circle.  After my research I came to a definite conclusion. I was a terrible person. I was responsible for my mother’s death. There seemed to be only one solution: Become a scientist. Like millions of sinners before me, I chose redemption. Science offers the promise of reason. It answers the question that haunted me every day: Why?  I had always loved biology but wasn’t so sure about graduate school. With my mom’s death I was suddenly alone in the world and desperate to make amends. It was this semi-delusional state that led me to the Ph.D. program, made me fall in love with molecular biology, and ultimately put an H.I.V.-laced needle in my hand.  I looked at the little mouse in front of me. How could I have done something so foolish? No one was supposed to do this risky procedure alone. I knew what I was supposed to do next — I had written the safety procedure myself. I should call for help and then begin washing the wound, taking my time to prevent infection. But what about the mouse, and its littermates still waiting in their cage? They were all under anesthetic, and if I left their masks on for too long, they would die.  Most accidental needle sticks occurring in a hospital don’t result in an infection. But inside the needle that stuck my finger was a highly concentrated virus designed to overwhelm and take over the body. I needed antiviral therapy immediately, within the hour, to reduce my chance of being infected. And yet I did nothing.  Instead, I returned to the procedure. I prepared another needle, gave the mouse the deadly dose and stopped the anesthesia. Tenderly, I placed the mouse back in its cage, then watched to make sure the drug wore off.  Only after repeating the procedure with each mouse and cleaning the work station did I allow myself to break down. I washed my shaking hands for 15 minutes, the minutes seemingly stretching into eternity. As I scrubbed the iodine soap into the tiny wound, a few tears fell on my cheeks. I willed myself to stop, to be calm. And then, before the hour was up, I walked into my academic adviser’s office and told her what had happened.  After a month of antiretroviral medication, I found I was lucky. I didn’t get H.I.V. The mice were not so lucky. As Steinbeck wrote, “Trouble with mice is you always kill ’em.” Except in science you don’t say kill. You say sacrifice. Usually it’s abbreviated to “sac” as in “I sac’d the mice.” I had loved those mice, cared for them from birth to death. But I had also injected them with millions of human stem cells, and then with a virus that had killed an estimated 36 million humans.  When I sacrificed them it made way for a new way of treating H.I.V. That strategy, using a gene therapy to cure the disease, is now being pursued in human clinical trials. Perhaps it will someday be worth it and the brief, brutish lives of those mice will save many humans.  Whether you’re speaking of mice or mothers, when you love someone you want to understand their death. There needs to be a reason. I will never know why my mom had to die. Perhaps that’s why I tried to give meaning to the lives of those mice. I just hope that they didn’t suffer. I hope none of us do.  Nathalia Holt is the author of “Cured: How the Berlin Patients Defeated HIV and Forever Changed Medical Science.”
Too many deaths have no meaning. I needed these animals’ lives to be part of the fight against H.I.V.