The SARS toll reached some daunting milestones last week: more than 500 deaths reported worldwide and more than 7,000 infections.

World health authorities also said the illness was more deadly than previously thought, raising the death rate to about 15 percent.

In recent weeks, companies have begun efforts to develop diagnostic tests, treatments, and cures to combat SARS - severe acute respiratory syndrome.

Whitehouse Station-based Merck & Co., one of the world's largest drug and vaccine makers, has started working on developing vaccines and therapeutics. CEO Ray Gilmartin called it a top priority.

Tony Ford-Hutchinson is at the fore of Merck's program. A British native with 21 years in research at the company, Ford-Hutchinson, 56, heads worldwide basic research for Merck, splitting time between offices in Rahway and West Point, Pa.

In an interview last week, Ford-Hutchinson spoke about SARS overall and Merck's efforts in fighting what he described as a "nasty disease."

Q. How much do we know right now about SARS?

It's caused by a type of virus which has been known for a long time, and we in fact get infected by this virus - which is called a coronavirus. In fact, it's one of the principal causes of the common cold. And it's also widely present in various animal populations, particularly birds and pigs for example. One of the ideas about many diseases is they jump from animal species into people. That's how the original flu outbreaks occurred for example, and they were transmitted in that same part of China, where this disease started, by transmission from animals to people.

These, what we call coronaviruses, come in many flavors. The one that's now infecting people is different from the one that causes the common cold. The one that causes the common cold just affects the nasal passages. This one goes deep down into the lungs right into the smallest parts of the lungs and infects those, which is why you get these very severe pneumonias. And the body reacts to this explosive growth of virus in the lungs. In fact, it's partly the body's reaction to the virus in the lung which killed people.

Q. Is what's known enough to find a cure, or is more research needed?

The principles of what's there allow us to develop vaccine approaches and therapeutic approaches. Just because you know the genomic sequence, it doesn't immediately mean you can solve the problem.

We've known the genomic sequence of HIV for a long time, but we obviously don't have a cure. But it does allow you very rational approaches, which we immediately started working on as soon as we realized what a problem we had here.

Q. What does Merck's SARS effort involve?

There are really three approaches we're using. The first is to develop a vaccine. We obviously are a big vaccine organization so we will use some of the experience we've got with some of our existing vaccine programs, such as the HIV vaccine program and the human papillomavirus vaccine program, which is to prevent cancer of the cervix. Developing a vaccine is not going to be trivial; we already know that because people have tried to make coronavirus vaccines for treatment of cats for example, which can get infected by these things. It's not simply a matter of taking the virus and disabling it and that will develop a vaccine as some people have sort of suggested. This is going to be a much more complicated process, in my opinion.

The second approach is to develop therapeutics, and those can be used in two ways. They could be used for the treatment of patients who've got SARS, and what could be very useful is for the prophylactic treatment of patients who are exposed to people who do have SARS, like health-care workers and family members. For those who have got this close transmission going on, it would be really nice to have a drug you can take like taking antibiotics for weeks to prevent you from developing the disease. That would obviously be advantageous.

A vaccine is going to take a long time to make. This is not going to come quickly. Therapeutics could come more quickly because again there are commonalties between the SARS virus and some of the viruses that we've been working on in the past. For example, we have a program aimed at hepatitis C. Both the SARS virus and the hepatitis C virus have a common target inside it, which is called polymerase [an enzyme]. We've developed drugs that target the hepatitis C polymerase. We're looking to see if those will hit the SARS virus polymerase.

Another approach is from the HIV area. These viruses have to penetrate cells, so they have cell entry mechanisms.The SARS virus seems to use a similar entry mechanism. Drugs have been developed for preventing HIV entry. You could envisage making similar types of entry blockers which would block the SARS virus entry, which again could be used as therapeutics.

Q. Is Merck focused on one area more than the others?

No. They're independent research groups. It's the kind of thing that really gets people mobilized at Merck. We don't really think about the commercial implications about it at this stage, we think about how it could be a major problem down the road. We rapidly mobilized all the people working in the vaccine area and the antiviral area, stopped some of our current programs and put them on hold while we threw the people at this problem.

Q. Could you elaborate how much resources?

It's difficult to say how many people, because people move in and out of projects. We started off as soon as this became apparent. We were invited down by [Health and Human Services Secretary] Tommy Thompson to go hear presentations of what was going on. Before that we had a big teleconference call with the CDC [Centers for Disease Control] and the NIH [National Institutes of Health]. As soon as it became apparent what was going on here, we rapidly threw resources at it.

It's more when you get in the late stage development that you get huge numbers of people when you're doing clinical trials. At the early stage it can be done with a reasonable number of people. But we had all the facilities. And it turned out we had people in the lab who had worked on coronaviruses in their previous lives before they joined Merck. It actually turned out we had a lot of in-house expertise around coronavirus, which was kind of nice.

Q. Is there something about the virus already that makes it a "nasty disease," say compared to HIV?

The HIV is a very different type of virus. It's what's called a retrovirus. It inserts itself in your genome so you can't get rid of it. This is not a retrovirus, so if you have a therapeutic you can treat it.

Influenza started off as a huge pandemic [after World War I]. The first season in southeast China was relatively mild and in the next two seasons is when all these millions of people died. The worry is what will happen in the next two seasons.

Q. Is that kind of scenario a possibility here, just the sense that it could be that much more dramatic the next two years?

It could be. The trouble is it got into parts of rural China. It's going to be very difficult to get rid of. We don't know where it came from either. It's not as infectious as flu, but it's more lethal.

Q. In terms of when treatments or vaccines will be developed, do you have a sense of any kind of timetable?

Vaccines will take years. Therapeutics can occur quicker. It's really difficult to quote timelines as we've only been working on it for about three weeks.