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: