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Molecule shows promise in treating bacterial infection

Published online 24 April 2014

Youssef Mansour

Low doses of a synthetic polymer of a naturally-occurring molecule might help curb deadly bacterial infections of Streptococcus pneumoniae and Neisseria meningitidis.

An important way the body defends itself against pathogens is through the complement system, which either degrades the bacterial membranes directly or marks the bacteria for degradation by immune cells.

A team led by Wilhelm Schwaeble at the University of Leicester in the UK and involving researchers from Saudi Arabia, Egypt, Iraq and Pakistan, including Youssif Mohammed Ali, from both the University of Leicester and Mansoura University, Egypt, found that low levels of properdin (Pn) — a long synthetic polymer of physiologic properdin — activates the complement system more so than the native molecule, publishing their findings in PNAS.

Through in-vitro studies, the researchers found that Pn is more active in recruiting complement components from human and mouse sera to the surface of both bacteria when compared to native properdin.

Mice infected with S. pneumoniae and N. meningitidis were used to investigate potential therapeutic applications. Low doses of Pn administered before infection with N. meningitidis caused a 90% survival whereas all control mice died. For S. pneumoniae infected mice, Pn application significantly prolonged survival rates and decreased bacterial load in blood.

Pn is expected to be of promise in combination therapies against multi-drug resistant strains of S. pneumoniae and N. meningitidis. "This new therapy is likely to provide a broad coverage against all kinds of pathogens including viruses and most likely also parasites" adds Schwaeble.


  1. Ali, Y.M. et al. Low-dose recombinant properdin provides substantial protection against Streptococcus pneumoniae and Neisseria meningitidis infection. PNAS (2014) doi:10.1073/pnas.1401011111