EpidEmiologyIn 2001, the possibility of an infectious component in the etiology of obesity was raised by Dhurandhar introducing the term "infectobesity" (1). In particular, support for Adenovirus type 36 (Ad-36) as a contributor to the obesity epidemic was found in chickens, mice and nonhuman primates (1-6). In 2005, a significant (relative risk = 2.7, P < 0.001) association between obesity and the presence of Ad-36 neutralizing antibodies in human serum was described in the United States by Atkinson et al. (7). Recently, subjects harboring Ad-36 DNA in their adipose tissue due to natural infection were described (8). To the best of our knowledge, very limited Ad-36 data in humans outside the United States are available, e.g., in Korean children as described by Atkinson et al. (9). Therefore our study explored this possible association in the Dutch and Belgian population data.
Methods and ProceduresIn total, 509 serum samples of four groups of patients were analyzed for Ad-36 antibodies, including 128 Dutch health-care students, 131 Dutch obese patients (BMI range 27-40 kg/m 2 ), 127 Belgian twinmembers and 123 Belgian blood donors. The selected twin-members included 62 subjects with overweight (BMI >25 kg/m 2 ) and 65 lean subjects (BMI <21.5 kg/m 2 ). The presence of antibodies to Ad-36 in serum was determined using the "constant virus-decreasing serum" method and, according to Atkinson, the cutoff titer used to determine positivity was 1:8 (7).PCR was used to determine whether adenoviral DNA was present in visceral adipose tissue of 31 severely obese surgical patients of the Netherlands. After an in-house preliminary comparison of three different ways to extract a highest yield of total DNA from human visceral adipose tissue (data not shown), DNA was extracted from 10 mg adipose tissue using the MagnaLyser, Proteinase K, MagnaPure LC instrument and the total DNA extraction kit (Roche Diagnostics, Almere, the Netherlands). Prior to isolation, the adipose tissue was spiked with known concentrations of an extraction and amplification control. The real-time PCR used for quantification of Adenoviral DNA was based on primers described by Echavarria et al. (10), and detection of Ad-36 DNA was confirmed by testing reference Ad-36 ATCC strain VR-913 (data not shown). The quality of the assay was assured by positive and negative controls as well as a test on amplification inhibition in each sample by an external amplification control. The analytical sensitivity of the entire assay was determined as <5.0 adenoviral DNA copies per PCR.Statistical analysis including logistic regression analysis was performed using SPSS, version 15 (SPSS, Chicago, IL).The study was approved by the local ethics committee.
resultsAn overall Ad-36 seroprevalence of 5.5% was found in 509 persons. In different patient subgroups, seroprevalence ranged Adenovirus infection has been shown to increase adiposity in chickens, mice, and nonhuman primates. Adenovirus type 36 (Ad-36) DNA was detected in adipose tissues in these animal trials. In the Uni...
