The controversy over whether Robert Gallo was robbed of a Nobel Prize in Medicine may end up lasting as long as the drawn-out battle over the discovery honoured by that prize.

A letter published in Science last week is the latest salvo in the flap over the Nobel, half of which was awarded last October to Françoise Barré-Sinoussi and Luc Montagnier for the discovery of HIV, the virus that causes AIDS. Both scientists were at the Pasteur Institute in Paris in the 1980s; Gallo, at the time, was at the US National Cancer Institute. The French and US scientists fought for years over who actually deserved credit for the discovery, and finally agreed to share credit in 1987. But the Nobel committee seems to have broken the truce by shunning Gallo and instead giving half the prize to German Harald zur Hausen for his work on the human papilloma virus.

The Science letter calls Gallo “an unsung hero” and argues, “Without Gallo’s contributions, the relevance of this virus to AIDS might not have been recognized for years… Gallo’s contributions should not go unrecognized.”

Guido Poli of the San Raffaele University and Scientific Institute in Milan organized the Science letter because, he wrote in an email to Nature, “I felt, and essentially all the others who signed the letter felt, that there was a strong “anti-Gallo” bias in the decision of assigning the 2008 Nobel Prize in Medicine.”

More than 100 scientists signed the letter, including many leaders in the HIV field.

Poli, who worked at the NIH for seven years, told Nature: “I witnessed the development of AIDS research since its first years and, although I was, and still am, proud as [a] European for the contribution of French and UK investigators in particular, I consider the exclusion of US research, and of Bob Gallo in particular, a distortion of such an important milestone in modern scientific history.”

Gallo’s grandparents were Italian, as are many of the scientists who signed the letter defending him. Italian newspapers also buzzed with speculation last year that Italian physicist Nicola Cabibbo was unfairly snubbed by the Nobel committee.