A check that detects antibodies in opposition to Zika virus in samples of blood serum with excessive specificity—and therefore a low threat of cross-reaction with associated microorganisms comparable to dengue virus—is ready to enter the Brazilian market earlier than 2018 is out.
The technique was designed by Brazilian scientists. Technology agency Inovatech, with the help from the São Paulo Research Foundation— FAPESP by way of its Innovative Research in Small Business Program (PIPE), developed the check in collaboration with scientists on the University of São Paulo’s Biomedical Science Institute (ICB-USP) and on the Butantan Institute.
“We’re within the remaining phases of growing a serological check to detect immunoglobulin G (IgG) antibodies, which stay within the organism for a few years after an infection, offering lifelong immunity. We count on it to be authorized on the market within the second half of this 12 months,” stated Danielle Bruna Leal de Oliveira, a researcher at ICB-USP’s Clinical & Molecular Virology Laboratory and principal investigator for the mission.
Since the creation in 2016 of the Zika Virus Research Network in São Paulo (Rede Zika), which is supported by FAPESP, growing this sort of diagnostic technique has been thought-about a precedence.
A software of this sort, in keeping with the scientists, is crucial for answering a number of strategic questions for any plan of motion in opposition to the illness: What is the precise measurement of the epidemic (distinguishing extra exactly between circumstances of dengue and Zika, in each present and previous outbreaks)? What proportion of pregnant ladies are contaminated (and therefore immune)? How many ladies threat giving delivery to infants with neurological issues attributable to congenital an infection?
“The concept is to incorporate this check within the prenatal examination course of,” Oliveira stated. “If we will do this, pregnant women with a detrimental outcome [meaning they have never been infected]will take extra precautions, comparable to avoiding journey to high-risk areas and utilizing insect repellent. Meanwhile, those that are immune will have the ability to cease worrying.”
According to Oliveira, presently out there diagnostic assessments both work solely within the acute part of an infection—as is the case with the molecular technique (real-time PCR) and chromatography, which detect viral RNA within the bloodstream—or detect Zika antibodies with low specificity.
“The specificity of the serological assessments presently available on the market falls inside the 69%-75% vary. So there’s at the least a 25% likelihood of a false constructive if the affected person was contaminated by dengue virus prior to now. Our check’s specificity is 93% for Zika,” Oliveira stated.
Like its predecessors, the check developed by Inovatech is predicated on a strategy often known as ELISA, an acronym for enzyme-linked immunosorbent assay. The platform consists of a microtiter plate with 96 tiny wells to which adheres a viral protein acknowledged by the human immune system.
The wells are crammed with blood serum from as much as 94 sufferers, with two or extra being reserved for controls. In the case of prior contact with Zika, IgG antibodies adhere to the viral protein, which is later detected by a colorimetric assay (constructive and detrimental samples purchase totally different colorings).
“One of the difficulties related to the tactic is that the viral protein generally used, NS1, could be very related in all flaviviruses [the family Flaviridae includes dengue, Zika and yellow fever, among others]. To clear up this downside, we used an edited model of the protein, choosing solely probably the most Zika-specific a part of the molecule,” Oliveira defined. This “truncated” model of NS1 (δNS1) was developed by Luis Carlos de Souza Ferreira and his staff at ICB-USP.
To scale back the chance of cross-reaction with dengue virus nonetheless additional, Inovatech’s researchers added one other stage to the assay. Before the blood serum from sufferers is positioned within the ELISA plate in touch with δNS1, it’s uncovered to proteins from dengue virus, with the purpose of extracting all antibodies in opposition to this pathogen from the samples.
“The downside is that it takes a bit longer to get a outcome—about three hours, in contrast with two hours and twenty minutes for standard ELISA—however we’re engaged on a method to make it sooner. The objective is that it needs to be faster than the usual technique as a result of it is designed to be used by hospitals in affected person screening,” Oliveira stated.
Selected in a call for proposals (in Portuguese) issued in 2016 underneath the aegis of an settlement between FAPESP and FINEP, the Brazilian Innovation Agency, the mission coordinated by Oliveira goals to create a quick, low-cost serological check to detect each IgG and IgM (immunoglobulin M), which stays within the organism for as much as about 4 months after the tip of an infection by Zika.
“We targeted on IgG all through 2017, and this 12 months, we’re specializing in the event of a strategy to detect IgM,” Oliveira stated.
Her group will likely be assisted by ICB-USP researchers Edison Luiz Durigon and Luiz Carlos Ferreira, in addition to Butantan Institute researchers Roxane Piazza and Viviane Botosso.
Although the time taken to acquire a outcome should be additional lowered, the low-cost a part of the mission’s objective has been achieved. Oliveira estimates the price of the assay to detect IgG at about BRL 10-12 per affected person (now about USD Three.00-Three.70).
Inovatech has additionally accomplished one other necessary step towards bringing its product to market: it has gained a Manufacturing Best Practice (BPF) certificates from ANVISA, the nationwide well being surveillance company. The first batches for experimental use are already being produced.