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New results evidence new biomarkers for early diagnosis of P. aeruginosa infections

Pseudomonas aeruginosa is a common multidrug-resistant pathogen that causes acute and chronic infections. However, P. aeruginosa, as many other bacterial species, has developed resistance to antibiotics being difficult to treat. For this reason diagnostic methods allowing detection at early  stages of the infection are required  and, therefore, efficient biomarkers of infection are very helpful. These fast diagnosis will help on the subsequent therapeutic treatment.

The Nb4D group of CIBER-BBN and IQAC-CSIC (led by M.-Pilar Marco) has recently conducted a research to develop a highly sensitive, specific and reliable immunochemical assay to detect pyocyanin (PYO), one of the most important virulence factors of Pseudomonas aeruginosa.

The assay uses a high-affinity monoclonal antibody produced by the unit 2 of the ICTS NANBIOSIS Custom Antibody Service (CAbS) (Dr. Núria Pascual).

The microplate-based ELISA developed is able to achieve a limit of detection (LoD) of 0.07 nM, which is much lower than the concentrations reported to be found in clinical samples (130 µM in sputa and 2.8 µM in ear secretions). The ELISA has allowed the investigation of the release kinetics of PYO and 1-OHphz (the main metabolite of PYO) of clinical isolates from P. aeruginosa-infected patients. Significant differences have been found between clinical isolates obtained from patients suffering an acute or a chronic infection (~6,000 nM vs. ~8 nM of PYO content, respectively).

The results found point to a real potential of PYO as a biomarker of P. aeruginosa infection and the possibility to use such virulence factor also as a biomarker for patient stratification and for an effective management of these kinds of infections.

Article of referece:

Rodriguez-Urretavizcaya, B., Pascual, N., Pastells, C., Martin-Gomez, M.-T., Vilaplana, Ll.*, Marco. M.-P. (2021). “Diagnosis and Stratification of Pseudomonas aeruginosa Infected Patients by Immunochemical Quantitative Determination of Pyocyanin From Clinical Bacterial Isolates.” Frontiers in Cellular and Infection Microbiology 11(1215). https://doi.org/10.1016/j.jmbbm.2021.104793

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Nanobodies for biosening at the European Biosensor Symposium digital seminars

Next November 8, the researcher of NANBIOSIS U2 Custom Antibody Service (CAbS)  J.-Pablo Salvador will host the Seminar “Nanobodies for biosensing” in the framework of European Biosensor Symposium digital seminar series which are schedulled on the third Tuesday of every month.

Nanobodies® (Nbs) are the recombinant binding domain from the heavy chain antibodies tipically produced from camèlids.  Besides their great potential as molecules in drug development, Nanobodies possess excellent functional properties that aid in their development for diagnostic tools. In this seminar, Dr. Salvador will explain the the outstanding properties of Nanobodies. Three graduate student speaker and up to five graduate student poster presenters will will take the opportunity to show different applications in the biosensing area.

The online event will take place on 16th November at 18:00 

Registration is free.

Further information on the European Biosensor Symposium digital seminars

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High quality antibodies for very challenging projects

Researchers of Nb4D group – Unit 2 of the ICTS NANBIOSIS (led by Pilar Marco, from CIBER-BBN and the IQAC-CSIC) have participated in Expoquimia 2021, the International Chemistry Meeting, which took place from 14 to September 17 at the Fira de Barcelona.

The researchers presented their work in several projects: the FoodSmartPhone project (MSCA-ITN-720325 action), the QS4CF (RTI2018-096278-B-C21), the QS-Motion (TV32018-201825-30-31) and on the PoC4CoV project (PIE-202050E090; PTI Salud Global, CSIC).

Research at the FoodSmartPhone(MSCA-ITN-720325 action) is focus on developing devices for the monitoring of contaminants of interest in food safety through the use of mobile phones. The production of the necessary antibodies for the detection of antibiotics and pesticides has been carried out by NANBIOSIS U2 Custom Antibody Service (CAbS). These are very specific monoclonal antibodies against pesticides, used by researchers Klaudia Kopper and Julian Guercetti to bind them to the functionalized surface and implemented in plasmonic detection sensors for antibiotics in milk and electrochemical biosensors for the detection of pesticides in cereals.

The scientific activity within the QS4CF (RTI2018-096278-B-C21) and QS-Motion (TV32018-201825-30-31) is focused on the Quorum Sensing communication system as an strategy to develop more efficient and specific diagnostic tools and therapeutic approaches to diagnose and treat P. aeruginosa and S. aureus infections.

The PoC4CoV project (PTI Salud Global, CSIC) seeks a comprehensive approach to diagnose COVID-19 developing devices to detect genetic material and proteins of the SARS-CoV2 virus, but also the response of the host against the infection. High quality antibodies against SARS-CoV-2 structural proteins (spike and nucleocapsid) have been produced by CAbS at NANBIOSIS

The camera flash is able to excite the functionalized surface of the chip and generate the specific response to the contaminant. This signal is picked up by the mobile through a Bluetooth connection and quantified.

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Prof. Pilar Marco, in the program “Meridiano Turing” of RTVE explains the COVID-19 tests.

The last edition of the program “Meridiano Turing” of RTVE interviews Maria Pilar Marco Head of CIBER-BBN and IQAC-CSIC group Nb4D and NANBIOSIS-ICTS Unit 2 Custom Antibody Service (CAbS), Cesar Fernández (Head of the Chemical Transducers Group at IMB-CNM, CSIC) and María Cruz Minguillón (EGAR group at IDAEA)

Pilar Marco y César Fernández, the authors of the block of the CSIC’s report entitled “Containment and diagnosis“, explain wich is the best way to diagnose COVID and how reliable are the tests in this moment.

What is needed is to detect an infection -says Pilar Marco- is viral material and we have two types of tests to detect viral material:
– Those that detect the viral RMA, which is the genetic material of the virus. These test known as “PCR”, were the first to be used and are quite reliable PCR is a technology that expands the genetic material, making many copies what makes it possible to detect the viral material with very low viral load
– And during the month of September have became famous what are known as the “antigen tests” (they also came out at the beginning, but they were of low quality). These tests do not detect the genetic material but the structural proteins of the virus.

Serological tests should not be used to diagnose an infection because they do not detect the virus, what they detect is the reaction that the host has in the presence of an infection, that is, the antibodies that our body produces to defend itself against the infection and this occurs from the first moment but is not detectable until practically seven days after being infected. Therefore serological tests have limited utility to diagnose the infection, they serve to monitor the evolution and immunological status of the patient, if he is producing antibodies against the virus and how it evolves The virus remains elevated for months, but it does not mean that if you have had the disease and the rsults fo serological tests are negative, you are not prepared to face the virus, since we have memory cells that will surely produce antibodies again.

Cesar Fernández explains that the sample is the same in PCR and antigen tests, but the time it takes to obtain an answer is different. Both type of tests are recommended depending on the situation and the environment in which they are used, PCR tests have been used more massively and are more reliable in the sense that they let out much fewer positives, the number of false negatives they provide is very low, but they are also more expensive tests and need more time from the moment the sample is taken until the result is obtained (minimum 24 hours) since they are carried out in clinical analysis laboratories. The antigen tests can be carried out in 15-30 minutes in the place where the sample is taken and their cost is very low compared to that of the PCR, which is why they are very useful for screening studies of the levels infection that may exist in a community. Currently, work is being done on carrying out the antigen tests in saliva, this would facilitate the taking of samples and would not generate practically social rejection. Studies are also being done on the use of nasal smears in which the sample is taken at the beginning of the nasal cavity, resulting in much less annoying. Antigen tests due to their low cost and ease use open the possibility of performing in a very repetitive way.

Regarding the measurement of viral load, it is given by the PCR, while in the antigen tests the detection is visual, a colored line appears, similar to the pregnancy tests, with greater or lesser intensity, with which the information they give on viral load is semi-quantitative, that is, the interpretation is quite subjective.
The viral load of the disease appears a few days before sinthoms are shown (the peak is two days before) and can be spread to other people. This also occurs with asymptomatic infected people, with the only difference that, after this peak, the viral load falls very quickly and the disease does not appear.

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PILAR MARCO, Scientific Director of NANBIOSIS U2, interviewed by CIBER-BBN ISCIII Bulletin

Pilar Marco, Scientific Director of NANBIOSIS U2 Custom Antibody Service (CAbS) has been highlighted in the January Bulletin of CIBER-BBN ISCIII

In the interview, among other topics Prof. Pilar Marco talks about diagnostic devices based on nanobiosensors and the extraordinary impact that these technologies could have on health in the coming decades.

Her research group Nb4D (Nanobiotechnology for Diagnosis) has an important collection of specific antibodies for different biomarkers and the CIBER-BNN/IQAC-CSIS platform CAbS (Custom Antibody Service) that constitutes the unit 2 of NANBIOSIS, they offer the possibility of producing specific and immunoreactive antibodies with the necessary expertise to generate antibodies “a la carte”, that is, being able to modulate to some extent the affinity and selectivity of these biomolecules, depending on the needs of each project. “And we do this, -Prof Marco explains- not only for molecules with high immunogenic capacity such as most proteins, but also for low molecular weight molecules, which in themselves are not capable of generating an immune response”. They are also able to chemically modify these antibodies and bind them to nanoparticles with defined optical, electrochemical or magnetic properties, thus converting them into nanoprobes able to detect biomarkers and generate an optical or electrochemical signal. We can also incorporate them in a controlled manner in transducer devices designed based on the latest advances in micro (nano) electronics to develop a new generation of diagnostic devices, much more sensitive and reliable, capable of providing quick answers and allowing a more accurate diagnosis early and accurate.

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