I do not know how popular is the English version of the Latin motto Lupus pilum mutat, non mentem, in Italian, however, it is very frequently used and even with a negative or a positive meaning. The negative component is emphasized for vices, which cannot be easily abandoned; the positive component is a strong determination, motivated stubbornness.
Last week the Latin motto with the positive meaning came to my mind at the end of the Lectio Magistralis on The role of pathogens in human cancers, held on Friday April 12th at Istituto Nazionale Tumori “Fond Pascale” Naples-IT, by the Nobel Laureate Prof. Dr. Harald zur Hausen. A Nobel Laureate in Medicine (2008), retired almost 10 years ago, could be just telling the story of his genial intuition, the discovery and the scientific activity (>300 indexed publications). People would be already overwhelmed by his knowledge and his accomplishments. But Harald, instead, describes new ideas and a new scientific project. Almost 40 years since the initial hypothesis of the papillomavirus role in human cancer (particularly cervical cancer), in open contrast with the scientific community favoring the role of herpes viruses (HSV-2), he is launching a new hypothesis on the role of viruses in colon cancer. It is true: a hunter will remain always a hunter, expert in chasing his prey.
The current challenge is, however, much more demanding, given that colon cancer has been considered for years the paradigm of cancers due to genetic damages and never been associated to pathogens.
Which data are supporting the role of pathogens in colon cancers?
The increased incidence of colon cancer in populations eating raw bovine meat (1). Moreover differences are clearly evident among populations eating meat from different bovine species, with lower incidence in populations eating Tibetan Yak (Bos mutus) in comparison to populations eating meat from Euro-Asiatic bovines (Bos taurus) and Indian Zebu (Bos indicus) or their hybrids Bos taurus Africanus (such as Sanga or the Ugandan race Ankole-Watusi). He suggests that bos taurus is the main species able to transmit to humans pathogens, to which the bovines have different susceptibility. It is relevant, in this respect, to report the lower susceptibility of the Bos indicus to Rinderpest, which favored the large distribution of the Bos taurus Africanus in the African Regions.
How solid are these data? are they only tentative claims? how much will take to get reliable and consistent results?
From the epidemiological point of view the data will need more accurate information, given that at the moment there is only a generic distinction between white meat (i.e. chicken, rabbit, etc..) and red meat (bovine, equine, swine, etc..) without any distinction between species.
From the microbiological point of view several pathogens could be involved, including the torque teno virus (TTV) of the new anelloviridae family (2,3).
If the subject is so controversial and complex, why to get involved with it? Ulixes in Dante’s poem would have replied:
Ye were not made to live like unto brutes,
But for pursuit of virtue and of knowledge.
(The Divine Comedy, Inferno, Canto XXV, 119, 120)
Harald, instead, simply stressed the need to know the necessary role (also if not sufficient) of a pathogen in order to reduce or limit the exposure to it and eventually to make a vaccine.
What enthusiasm and healthy recklessness in a 77-year old wise man, who encourages young scientists to fearless pursue innovative routes and to analyze with care and criticism also those subjects, which seem to be clearly solved and no one would have further discussed.
1. zur Hausen H. Red meat consumption and cancer: reasons to suspect involvement of bovine infectious factors in colorectal cancer. Int J Cancer. 2012 Jun 1;130(11):2475-83. doi: 10.1002/ijc.27413;
2. de Villiers EM, Bulajic M, Nitsch C, Kecmanovic D, Pavlov M, Kopp-Schneider A, Löhr M. TTV infection in colorectal cancer tissues and normal mucosa. Int J Cancer. 2007 Nov 1;121(9):2109-12;
3. de Villiers EM, Borkosky SS, Kimmel R, Gunst K, Fei JW. The diversity of torque teno viruses: in vitro replication leads to the formation of additional replication-competent subviral molecules. J Virol. 2011 Jul;85(14):7284-95. doi: 10.1128/JVI.02472-10. Epub 2011 May 18