Uni­ver­si­ty full pro­fes­sor Séver­ine Padi­ol­leau is a research sci­en­tist at the GEC Enzy­mat­ic and Cel­lu­lar Engi­neer­ing Lab­o­ra­to­ry in the CNRS unit ded­i­cat­ed to biotech­nol­o­gy. She coor­di­nates an inter­dis­ci­pli­nary project on Lyme dis­ease involv­ing, in addi­tion to the GEC, the LMAC, Costech and the Saint-Côme poly­clin­ic, one of France’s cen­tres of exper­tise on the disease.

The most com­mon infec­tious dis­ease in France – with 40 000 new infec­tions and around 700 hos­pi­tal­i­sa­tions record­ed each year – Lyme dis­ease, or Lyme bor­re­lio­sis, is trans­mit­ted by tick bites and is most preva­lent in for­est areas. This is the case, for exam­ple, in the Com­piègne basin. The clin­i­cal signs of the dis­ease – short-term mem­o­ry loss, joint pain, headaches, per­sis­tent fatigue, etc. – often baf­fle gen­er­al prac­ti­tion­ers, who strug­gle to make the cor­rect diag­no­sis, leav­ing patients in a state of diag­nos­tic and ther­a­peu­tic uncertainty.

It was after read­ing an inter­view with Dr Ahed Zedan of the Saint-Côme poly­clin­ic in the region­al news­pa­per Le Cour­ri­er Picard that Séver­ine Padi­ol­leau decid­ed to con­tact him. At the same time, Dr Zedan had also tak­en the ini­tia­tive to con­tact Marc Shawky, uni­ver­si­ty pro­fes­sor and researcher at the UTC Costech Laboratory.

The idea of set­ting up this inter­dis­ci­pli­nary project thus took root. In addi­tion to Séver­ine Padi­ol­leau, the project involves Irene Maf­fuc­ci, senior lec­tur­er, and Stéphane Octave, respec­tive­ly a researcher in bioin­for­mat­ics and a research engi­neer in biol­o­gy at UTC’s GEC Lab., Marc Shawky, Miraine Felipe and Ghis­laine Gayraud, respec­tive­ly senior lec­tur­ers and uni­ver­si­ty pro­fes­sors, both researchers at UTC-LMAC, and Dr Ahed Zedan, from Côme Poly­clin­ique. The project is part­ly fund­ed by UTC, the Sor­bonne Uni­ver­si­ty Alliance, the Hauts-de-France Region and patient asso­ci­a­tions. “The ini­tial fund­ing came from patient asso­ci­a­tions, which enabled us to get the work start­ed,” explains Stéphane Octave.

“The key idea behind the biotech­nol­o­gy aspect of this project is to iden­ti­fy mol­e­c­u­lar probes capa­ble of recog­nis­ing the bac­te­ria that cause the infec­tion lead­ing to Lyme dis­ease. These mol­e­c­u­lar probes could be pro­tein, pep­tide or oth­er in ori­gin. We are cur­rent­ly focus­ing our work on oligonu­cleotide probes, called aptamers. These are strands of DNA or RNA nucle­ic acid which, due to the com­ple­men­tar­i­ty of their bases, adopt a very spe­cif­ic three-dimen­sion­al con­fig­u­ra­tion, enabling them to inter­act specif­i­cal­ly with a pre­vi­ous­ly iden­ti­fied tar­get. Like anti­bod­ies capa­ble of detect­ing a par­tic­u­lar anti­gen, aptamers can there­fore specif­i­cal­ly recog­nise a tar­get pro­tein. Fur­ther­more, as Lyme dis­ease is caused not by the pres­ence of a sin­gle bac­teri­um, but by con­t­a­m­i­na­tion involv­ing a group of bac­te­ria, the project aims to design sev­er­al mol­e­c­u­lar probes to simul­ta­ne­ous­ly detect a range of bac­te­ria. This is known as a mul­ti­plex test,” explains Séver­ine Padiolleau.

The serological approach: indirect detection

Cur­rent­ly, the detec­tion of Lyme dis­ease is based on a ‘sero­log­i­cal’ approach. In oth­er words, in cas­es of doubt for cer­tain patients, the doc­tor pre­scribes a blood test to check for the pres­ence of serum anti­bod­ies fol­low­ing infec­tion. “This is an indi­rect detec­tion method, as it does not look for the pres­ence of one or more bac­te­ria respon­si­ble for the infec­tion, but only for anti­bod­ies prov­ing that the patien­t’s immune sys­tem has react­ed. How­ev­er, this type of test is cur­rent­ly sub­ject to cau­tion. Hence the desire to devel­op direct diag­nos­tic tests, i.e., tests capa­ble of con­firm­ing the pres­ence of a bac­teri­um or com­plex of bac­te­ria, and also of iden­ti­fy­ing the bac­te­ria with which the patient has been infect­ed. One of the first exter­nal symp­toms is what is known as ery­the­ma migrans, which appears as con­cen­tric red cir­cles at the site of the bite. In this case, the doc­tor will be able to make an accu­rate diag­no­sis. How­ev­er, this exter­nal man­i­fes­ta­tion does not appear sys­tem­at­i­cal­ly in all patients. Some will there­fore devel­op oth­er symp­toms, which are much more dif­fi­cult for the doc­tor to iden­ti­fy because they are sim­i­lar to those caused by oth­er dis­eases,” points out Séver­ine Padiolleau.

In the absence of ery­the­ma migrans, a vis­i­ble mark­er of infec­tion, some patients will expe­ri­ence symp­toms sim­i­lar to those of influen­za – fever, fatigue, lack of con­cen­tra­tion, etc. – while oth­ers will expe­ri­ence joint, neu­ro­log­i­cal and/or der­ma­to­log­i­cal prob­lems, and some­times even car­diac prob­lems. The diver­si­ty of symp­toms is undoubt­ed­ly linked to the nature of each indi­vid­u­al’s con­sti­tu­tion. These are sit­u­a­tions in which doc­tors find them­selves help­less and for which the sero­log­i­cal approach remains unreliable.

Favouring a direct, multiplexed approach

What is the advan­tage of a direct approach like this? “It is a ques­tion of over­com­ing all the crit­i­cisms asso­ci­at­ed with the sero­log­i­cal approach. The idea is to devel­op one or more aptamers, each spe­cif­ic to the detec­tion of a pro­tein present on the sur­face of a par­tic­u­lar bac­teri­um. The aptamers could be cou­pled with dig­i­tal or elec­tron­ic biosen­sors to ensure reli­able, sen­si­tive and rapid detec­tion. In fact, our approach is unique in two ways, as we are aim­ing for direct detec­tion as well as a mul­ti­plexed approach. Mul­ti­plex­ing makes it pos­si­ble to con­firm in a sin­gle test that the patient has been infect­ed by a par­tic­u­lar bac­teri­um. In short, it iden­ti­fies the nature of the bac­te­r­i­al pan­el respon­si­ble in a sin­gle test. In addi­tion to enabling a more accu­rate and reli­able diag­no­sis, this method also has def­i­nite epi­demi­o­log­i­cal val­ue. This will enable us to say that, in the Oise region for exam­ple, we are more like­ly to encounter a cer­tain type of pathogen than those preva­lent in the moun­tains of East­ern France. It also pre­vents us from ‘miss­ing out’ a pathogen and declar­ing that the patient does not have Lyme dis­ease in the absence of a par­tic­u­lar bac­teri­um, since we are rely­ing on a com­plex of bac­te­ria. For the moment, we are estab­lish­ing so-called ‘proof of con­cept’ by tar­get­ing a rel­a­tive­ly uni­ver­sal pro­tein found on the sur­face of sev­er­al spiro­chetes com­mon­ly involved in Lyme dis­ease. Ulti­mate­ly, we hope to iden­ti­fy the pro­teins spe­cif­ic to each bac­teri­um in order to move on to mul­ti­plex­ing,” says Séver­ine Padiolleau.

MSD