First fatality

THE scientific community is deeply troubled. The 1st ever reported case of aids was not aids at all! That ends the certainty with which they so long had regarded the origin of the disease. David Ho, director of the Aaron Diamond Aids Research Centre, New York, claims that the original sample analysed and later reported in the July 4, 1990 issue of the Lancet were not from the 1959 patient, but came from a 1990 aids victim!

Was there a mix up in the Manchester lab, or a deliberate plant? The central figure of this controversy was David Carr, 25, who spent the last 5 years of his life at Manchester's Royal Infirmary. In December 1958 Carr complained of a series of health problems, like breathlessness, night sweat, tiredness and weight loss. Rapid and dramatic deterioration of his health followed and brown, scaly lesions appeared on his skin. He was admitted to the hospital on April 8, 1959, and died on August 31.

The reason for his death was pneumonia, caused by Pneumocytis carinii, an infection attacking the weakened immune system. His doctors wrote, "he was wasted, febrile and ill". Carr's unusual case was first described in the October 29, 1960 issue of the Lancet.

The '80's saw the advent of a new mysterious disease -- aids. After reading the medical literature on it, the 3 doctors -- Trevor Stretton, John Leonard, and George Williams, who handled David Carr's case, wrote to the Lancet in 1983 asking: did our patient have aids? The letter carried details about Carr's lifestyle. He was a bachelor and the doctors were not aware of his sexual orientation.

Seeing the interest generated, George Williams located the tissue samples, which he had taken from the patient's body 28 years ago. Slicing small pieces of tissue from every part of Carr's body, Williams had preserved more than 40 samples by embedding them in paraffin blocks.

Williams sent some tissue samples to Gerald Corbitt and Andrew Bailey of the hospital's virology unit in the late 1980s, when the polymerase chain reaction (PCR) technique was developed. The PCR is a sensitive technique which gives the genetic blueprint of all tissue samples by amplifying the DNA sequence.

Applying the technique to the samples, Corbitt and Bailey found the test positive for aids. Not convinced, Corbitt decided to conduct a proper "blind trial" where neither he nor his associate would be aware of the owners of the tissue samples. He then received 12 tissue samples from Williams, 6 of which belonged to Carr, and the rest to a man of similar age who had died in an accident the same year. Only Williams was aware of the tissue identity, as the codes of the test tubes containing the samples were with him.

Extreme precaution was taken while the blind experiment was underway, so as to avoid all possible forms of contamination. The experiment was repeated twice and the result was identical. Each time, 4 samples tested positive and 8 negative. On decoding, it was found that the 4 positive samples came from Carr's body.

The results, according to Corbitt, were better than expected. Hence Corbitt, Bailey and Williams wrote a letter to Lancet on July 9, 1990, to apprise them of their findings, resulting in a deluge of international publicity.

Somehow, the results did not convince David Ho, who is a professor of medicine and microbiology at the New York University School of Medicine. Contacting the Manchester research team in 1992, he enquired about the patient, and then asked for some tissue samples. He wanted to complete the genetic code sequencing which Corbitt and Bailey were unable to carry out successfully. Their partial sequencing had revealed the virus to be of the hiv-1 type.

The advanced facilities available with Ho's research centre enabled him to isolate the entire sequence of hiv easily. This was done in 1993, when he was sent processed dna from kidney tissue. This entire sequence was identical to the partial sequence isolated by Corbitt and Bailey, thus giving scientific confirmation to the fact that the virus came from the same patient.

Gerald Meyers, the director of hiv Sequence Database, at the usa's Los Alamos National laboratory in New Mexico and a world authority on the genetics of the virus, cast further doubts on the authenticity of the research by suggesting that the virus could possibly be a contaminant. To Meyers, only the virus just did not make any sense.

The aids virus is one of the fastest evolving life forms, with a dramatic changing speed. According to Meyers's estimates, all the hiv strains circulating in the world alter at the rate of about 1 per cent per year. This meant that the "1959 virus", which must have infected Carr earlier, should have been about 30 percent different from the 1990 strain.

Meyers thus pointed out that the supposed "1959 virus" was identical to those strains which were found in 1990 all over North America and Europe. He discounted the virus as an aberration.

Ho had identified "quasi species" of HIV from the original samples sent to him. That means the virus detected by him was present in swarms of slightly different forms, indicating that it was a genuine HIV infection with multiple copies of actively replicating virus, suggesting that it was not one-off contamination.

Another factor against any accidental contamination was the presence of an entire virus in the pcr test. This meant only 2 things -- either the tissue sample was really infected or that an entire clone had somehow got into the sample. But the clone theory was immediately discounted as Corbitt's laboratory did not use hiv clones.

Left with the feeling that there was a sample mix-up resulting in an incorrect sequence, the New York scientists asked the Manchester researchers for the actual tissue samples. Consequently, they received 9 tissue samples in their original paraffin blocks in February 1994.

Ho was unable to trace any HIV after performing the most sensitive and advanced PCR tests. He also performed DNA tests to confirm that all the tissues belonged to the same person. He then conducted the same tests on the tissues he had received earlier, which had tested HIV positive. The two sets belonged to two different people. To confirm this, Ho checked the size of the gene fragments. The HIV positive tissue generated large gene fragments, while the HIV negative produced small fragments. The theory that larger the gene fragment the more recent is the tissue (DNA gets degraded in older tissue), removed all doubts from Ho's mind that the positive set of tissue came from a patient who died in 1990.

The Lancet research will have to be protracted, in view of the present circumstances. Meanwhile, the doctors and researchers still have to deal with Carr's mystery illness and wonder -- who was the first confirmed case of AIDS, after all?