Vaccination alters your body odour

Immunisation can trigger a distinct change in your body odour, scientists have found for the first time.
"This work provides further evidence that it is possible to use odours to 'eavesdrop' on the immune system, suggesting that non-invasive disease detection may be possible even before the onset of observable symptoms," said Bruce Kimball, a researcher with the US Department of Agriculture (USDA).
"The results have potential implications regarding disease surveillance in wildlife populations and food safety, bio-terrorism, and human disease diagnosis," said Kimball.
In the study, 'bio-sensor' mice were trained to discriminate between urine odours from mice vaccinated against either the rabies virus (RV) or the West Nile virus (WNV).

All training and testing trials were conducted using a Y-maze with odours randomly assigned to each arm of the "Y."
The bio-sensor mice were also trained to differentiate between urine from mice treated with lipopolysaccharide (LPS), a bacterial toxin that activates the immune system, and untreated urine.

After completing training sessions, researchers conducted several validation trials using urine from unfamiliar individuals to exclude the possibility that individual odours, rather than treatment odours, were being detected.
Following validation trials, several rounds of testing sessions were conducted.
The bio-sensor mice clearly discriminated RV, WNV, and LPS urine odours from non-treated urine.
Furthermore, bio-sensors also were able to differentiate between the vaccines and LPS odours. However no discrimination was made between RV and WNV odours.

Together, the findings suggest that the two vaccines alter urine odour in similar ways, while an LPS-triggered immune response produces a qualitatively different body odour.
"This research indicates that there is a pathway between immune activation and changes in the body odour compounds, revealing yet another kind of information stored in body odours," said Gary Beauchamp from the Monell Chemical Senses Centre, an author on the paper.
"It is likely that humans also have the potential to communicate the same information, although much more research is needed to demonstrate this," said Beauchamp.
Based on the hypothesis that immune-activated odours may signal the presence of disease to other members of a species, ongoing studies are exploring how vaccination-induced odour changes may influence mouse social and reproductive behaviour.

The findings appear in the journal Physiology and Behaviour.