For HIV drugmakers, two heads are better than one -- especially if it can halve the number of pills a patient has to take.

The latest two to hook up are Gilead Sciences (NASDAQ:GILD) and Motley Fool Income Investor pick Johnson & Johnson (NYSE:JNJ). The duo announced yesterday that they'll develop a combination pill containing Gilead's Truvada and Johnson & Johnson's experimental drug TMC278.

Johnson & Johnson is testing TMC278 in phase 3 trials in combination with Truvada, so the partnership shouldn't come as much of a shock to anyone. Gilead will take the lead in getting the combo drug approved and the companies will combine efforts to market it.

It's a bit of a gamble to start development without an approval for TMC278, but presumably Gilead knows what it's doing; this isn't the first hook up for the HIV specialist. Gilead currently sells Atripla, a combination of Truvada and Bristol-Myers Squibb's (NYSE:BMY) Sustiva. Patients clearly enjoy the convenience; Atripla is on pace to overtake Truvada for the top spot on Gilead's sales roster, with sales growing 57% year over year compared to Truvada's 23% growth in the most recent quarter.

Gilead isn't the only one that thinks two virus killers are better than one. In April, GlaxoSmithKline (NYSE:GSK) and Pfizer (NYSE:PFE) set up a joint venture to sell their existing and in-development HIV drugs. The immediate advantage of the joint venture is sharing a sales force, which should help keep costs down, but the natural extension of the deal will be to combine drugs to make it more convenient for patients.

Sit back, have a cocktail of your own, and enjoy the show; the competition for HIV patients is just heating up.

A cocktail of Foolishness:

Pfizer is a Motley Fool Inside Value selection. Johnson & Johnson is an Income Investor recommendation. Try any of our Foolish newsletters today, free for 30 days

Fool contributor Brian Orelli, Ph.D., doesn't own shares of any company mentioned in this article. The Fool has a disclosure policy.