​London, Dec 15 (IANS) A cost-effective saliva test may have the potential to act as non-invasive marker of immunity and thus enable assessment of vaccination and protection against bacterial infections such as pneumococcal infections in the human body, a study has found.

Saliva test can be an attractive method of specimen collection particularly for children and the elderly, the researchers said.

"Saliva sampling is non-invasive, requires no specialist training or equipment, and may be more cost-effective," said lead author Jennifer Heaney from the University of Birmingham in Britain.

The study showed that IgG Pn antibodies in saliva correlated with antibody levels in serum in infants. 

Protection against bacterial infection is usually inferred by measuring antibody levels in blood serum.

But taking blood samples involves a number of logistical considerations and may not always be feasible, especially in developing countries or where children are involved. 


"The suggestion that antibody levels in saliva may be indicative of those in serum therefore has important implications for markers of immunity and vaccination in many parts of the world," Heaney added. 

Previous research showed that lower levels of antibodies in saliva are associated with of an elevated risk of mortality, and that saliva sampling to determine IgA secretion rate has the potential to be used as an indicator of overall health by professionals as part of a general check-up.

For the study, samples of both blood and saliva were taken from 72 healthy adults. Samples were then analysed to test for concentrations of IgG, IgM and IgA antibodies against 12 pneumococcal (Pn) antigens.

The results showed that in general, higher antibody concentrations in serum were associated with higher concentrations in saliva, with the strongest relationships observed for IgA antibodies.

The study was published in the journal Biomarkers.