Sunday, 29 May 2011

Obesity - symptom of a viral infection?

Type the search terms "obesity, adenovirus-36" into PubMed, the U.S. National Library of Medicine's online database of biomedical research, and you get 21 hits. In fact, the first report of a link between adenovirus infection and increased body fat was published in 2000 by Dhurandar et al1. This report not only showed that infection with adenovirus-36 increased body fat, but also highlighted the fact that cholesterol and triglycerides were decreased in animals infected with adenovirus-36.

By 2004 this research group had shown that neutralizing antibodies to adenovirus-36 are associated with obesity in humans and showed that infection with the virus seemesto enhance differentiation of pre-adipocytes2 (i.e. encouraged the formation of fat cells).

In 2007 Durhandar and co-workers showed that infection with adenovirus-36 not only enhanced differentiation of fat cells, but also decreased leptin levels and increased glucose uptake by fat cells. 3 Leptin is a hormone that regulates appetite and is secreted by fat cells. The group also suggested that infection could increase insulin sensitivity.

In 2010 and 2011 two studies reported no link between the presence of adenovirus-36 and body fat in individuals:

Goossens and co-workers found that adenovirus-36 does not play a role as a direct cause of BMI increase and obesity in humans in the Netherlands and Belgium.4 This iwas s in contrast to the United States, where Adenovirus-36 significantly correlates with obesity as illustrated by an Ad-36 seroprevalence of 30% in obese individuals and 11% in nonobese individuals. (Dr Atkinson replies here to the Goossens et al. study)

Broderick and co-workers showed no relationship between Ad-36 presence and obesity or serum cholesterol levels among US military personnel. 5 However, they did find a correlation between Ad-36 exposure and age, race and gender.

Recently, Waye has proposed a mechanism that involves oxidative stress in the pathology of Adenovirus-36 induced obesity. 6

At present there is still a lot of questions to be answered about the theory of viral-induced obesity. However, if obesity is caused by a virus it would be possible to prevent it by vaccinating humans against it. Obetech LLC is a company already investigating this possibility.

Image: human adenovirus



1 Dhurandhar NV, Israel BA, Kolesar JM, Mayhew GF, Cook ME, Atkinson RL.(2000) Increased adiposity in animals due to a human virus. Int J Obes Relat Metab Disord. 24: 989-96.

2 Vangipuram SD, Sheele J, Atkinson RL, Holland TC, Dhurandhar NV. (2004) A human adenovirus enhances preadipocyte differentiation. Obes Res. 12: 770-7.

3 Vangipuram SD, Yu M, Tian J, Stanhope KL, Pasarica M, Havel PJ, Heydari AR, Dhurandhar NV. (2007) Adipogenic human adenovirus-36 reduces leptin expression and secretion and increases glucose uptake by fat cells. Int J Obes (Lond). 31: 87-96. Epub 2006 May 16.

4 Goossens VJ, deJager SA, Grauls GE, Gielen M, Vlietinck RF, Derom CA, Loos RJ, Rensen SS, Buurman WA, Greve JW, van Baak MA, Wolffs PF, Bruggeman CA, Hoebe CJ. (2011) Obesity (Silver Spring). 19: 220-1. Epub 2009 Dec 10.

5 Broderick MP, Hansen CJ, Irvine M, Metzgar D, Campbell K, Baker C, Russell KL. (2010) Adenovirus 36 seropositivity is strongly associated with race and gender, but not obesity, among US military personnel. Int J Obes (Lond). 34: 302-8. Epub 2009 Nov 10.

6 Waye MM. (2011) New insights into how adenovirus might lead to obesity: An oxidative stress theory. Free Radic Res. May 26. [Epub ahead of print]