Usage of bacteriophages as an adjuvants in antibiotic therapy

Abstract

Kombinirani lijekovi koji sadrže mutirane fage i antibiotike moguća su alternativa konvencionalnim tretmanima s antibioticima protiv bakterijskih infekcija. Fag se mutira kako bi pojačano eksprimirao odabrane proteine koji reguliraju određene skupine gena, odnosno skupine gena na koje antibiotici ne djeluju izravno i time oslabe bakterijsku stanicu te tako pojačavaju uspješnost djelovanja antibiotika. Kombinirani lijekovi ciljaju na gene koji nisu esencijalni za bakterijsku stanicu, te na gene koji uzrokuju indukciju SOS odgovora u bakterijskim stanicama. SOS odgovor u bakterijskim stanicama inhibiran je tretiranjem s mutiranim fagom φlexA3 u kojem je gen lexA3 stavljen je pod kontrolu promotora PLtetO koji uzrokuje njegovo prekomjerno eksprimiranje. Djelovanje raznih klasa antibiotika (kvinoloni, aminoglikozidi, β-laktami) značajno je poboljšano korištenjem spomenutog faga. Osim toga, dokazano je da je mutirani fag φlexA3 u stanju značajno smanjiti broj otpornih stanica u populacijama koje su već bile izložene antibioticima. Klinička važnost faga φlexA3 vidljiva je iz njegove učinkovitosti u spašavanju zaraženih miševa. I druge skupine gena mogu se unijeti u bakteriofage, (SoxR, CsrA, OmpF) s ciljem da se poboljša baktericidna učinkovitost antibiotika i rezultati su bili veoma uspješni. Fagi su pogodni za ugradnju i više meta odjednom i tako nastaju višeciljni fagi koji ciljaju na višestruke receptore u bakterijskim stanicama i u nekim okruženjima oni pokazuju i znatno bolje rezultate od jednociljnih faga, kao npr. u biofilmovima.Combination therapy containing mutated phages and antibiotics is a possible alternative to conventional treatment with antibiotics only. Phages are changed to overexpress selected proteins that regulate a group of genes, or groups of genes that are not directly attacked by antibiotics. In that way, they weaken the bacterial cells, thus enhancing the improved effects of antibiotics. Combination therapy targets nonessential genes, or genes that induce the SOS response in bacterial cells. In the experiment bacteria was treated with mutated phage φlexA3. In this phage, the lexA3 gene was placed under the control of the synthetic PLtetO promoter which caused overexpression of lexA3. φlexA3 suppressed the SOS response induced by antibiotic (quinolones) and improved the bactericidal effect of the same antibiotic. Bactericidal effect of other class of antibiotic (amino glycosides, β-lactam antibiotics) was also considerably improved with usage of lexA3. They also found out that mutated phage φlexA3 is capable of reducing the number of bacterial cells that already have acquired antibiotic resistance. Clinical relevance of mutated phage φlexA3 is visible from its efficacy in preventing death in mice infected with bacteria. Also other gene networks where also targeted to produce effective antibiotic adjuvants (SoxR, CsrA, OmpF) that proved efficient. Mutated bacteriophages are well suited for incorporating multiple targets. The multitarget phage in some surroundings (for example, biofilm) showed better bactericidal effect compared with single-target relatives