BOSTON >> As a gay man, the Boston attorney thought he was doing the responsible thing when he asked his doctor to prescribe Truvada, a drug hailed as a way to halt the spread of AIDS. But when he tried to get long-term care insurance, Mutual of Omaha turned him down, saying it does not offer coverage to anyone who takes the drug.

Now, the man is planning to sue the insurer, alleging he was discriminated against because he is gay. He filed a complaint Wednesday with the Massachusetts Commission Against Discrimination, the first step in a lawsuit.

The man, who is identified only as John Doe in the complaint, said he wants to make sure that he and anyone else taking Truvada can get long-term care insurance, which covers daily, extended-care services for people with chronic illnesses or disabilities.

He also wants to ensure that people are not deterred from using Truvada because they fear they will face discrimination.

"I was shocked. I really was," Doe told The Associated Press in interview at the offices of Gay & Lesbian Advocates & Defenders, a Boston-based legal group that is representing him. He spoke on condition of anonymity because his complaint contains private medical information.

"I thought maybe they misunderstood me. I’m HIV-negative. I’m not HIV-positive. I was taking Truvada as a prophylactic."

Bennett Klein, director of GLAD’s AIDS Law Project, calls the decision "nonsensical."

"It’s really based on the stereotypes and the fears that are out there, that somehow gay male sexuality is inherently risky and unhealthy," Klein said. "We have a lot of bias about gay male sexuality in our society."

Truvada was first approved by the U.S. Food and Drug Administration in 2004 to be used in combination with other medications to treat people with HIV. In 2012, the FDA made it the first drug approved for pre-exposure prophylaxis (PrEP) to reduce the risk of HIV infection in uninfected people.

The Centers for Disease Control and Prevention says taking Truvada consistently has been shown to reduce the risk of HIV transmission in people who are at risk by up to 92 percent.

Critics of Truvada say widespread use could lead to an increase in condom-less sex and new HIV infections because people will forget to take the pill it every day.

Mutual of Omaha declined to comment on the complaint.

"We have not seen the complaint and it’s our practice not to comment on potential litigation," said Jim Nolan, a company spokesman.

Doe, a 61-year-old attorney and businessman who lives in Boston, said he began taking Truvada about a year ago after discussing it with his doctor. He said he has lost dozens of friends to AIDS and cannot understand the rationale behind rejecting his application for long-term coverage when Truvada is believed to reduce his risk of HIV. His long-time partner also is HIV-negative.

"I lived through the Holocaust of people dying from AIDS. I was doing my little part to stop that," he said.

He said he received a letter in April from a chief underwriter for Mutual of Omaha denying his appeal. "We do not offer coverage to anyone who takes the medication Truvada, regardless of whether it is prescribed to treat HIV infection, or is used for pre-exposure prophylaxis. This in accordance with our underwriting guidelines," the letter said, according to the complaint.

Doe alleges that Mutual of Omaha discriminated against him based on sexual orientation and disability, in this case, an assumption that Doe will in the future contract HIV, a health condition covered by the state’s antidiscrimination law.

Dr. Kenneth Mayer, a professor at Harvard Medical School and director of HIV Prevention Research at Beth Israel Deaconess Medical Center in Boston, said he doesn’t understand why Mutual of Omaha would reject an applicant for long-term care insurance because he is taking Truvada.

"The last thing we want to do is discourage people from using this preventive mediation," Mayer said. "The goal is to eradicate the number of new HIV infections."