Scientists monitor flu virus mutations in sewage samples

In July, the Institut Pasteur de São Paulo (IPSP) created a research group to monitor the emergence and spread of new strains of the influenza virus, which causes flu, in the capital of São Paulo.

Periodic collection of sewage samples makes it possible to identify which strains have entered circulation and which may pose a risk to human and animal health. It is also possible to predict the onset and peak of transmission, as well as the dynamics of circulation in the urban environment. The information will be passed on to public health authorities and will help in the development of a more effective and rapid vaccine against the disease.

The project at IPSP is expected to last four to five years and is funded by FAPESP.

Currently, the vaccines distributed by the Ministry of Health protect against the three types of influenza virus strains that have circulated the most in the Northern and Southern hemispheres. The problem is that the viruses in circulation are not always the same as those used in the vaccine. In addition to being diverse, influenza mutates rapidly. It is estimated that the effectiveness of the vaccine in a campaign varies from 40% to 60%, due to the suitability of the vaccine for the circulating strains and adaptation to the specificities of each one.

“This problem can be reduced with the new form of surveillance and a technology that makes it possible to update the vaccine more quickly, which is the objective of our research group,” virologist and biomedical scientist Rúbens Alves, coordinator of the Survivax research group: Laboratory of Genomic Surveillance and Innovation in Vaccines, told the IPSP Press Office.

According to Alves, the proposal to carry out surveillance using samples of wastewater from basic sanitation is a strategy that has proven to be very effective during the Covid-19 pandemic and has been used by more than one hundred countries and 293 universities.

“We will now be at the forefront of implementing this technology for influenza. In the case of coronavirus, it was possible to observe peaks in transmission in a given region two weeks in advance – information that was very useful for public health decision-making,” he said.

Currently, influenza virus surveillance is carried out by the World Health Organization’s (WHO) Global Influenza Surveillance Network, which is made up of laboratories spread around the world. They are responsible for monitoring circulating and potentially pandemic viruses, based on laboratory analyses. From this, every year, the WHO releases six to eight months in advance which strains should be used in the production of vaccines for the Southern Hemisphere, for use the following year.

“A large part of the monitoring included in this network depends on testing suspected cases of the disease. Monitoring via sewage allows for more representative coverage of the population, because it includes people who do not have access to health care or who choose not to go to the hospital, which also makes it less expensive, as it depends on fewer clinical exams. In addition, it is a system that allows for continuous monitoring, not only during the season when the virus is most circulating, which helps in assessing long-term trends and real-time tracking. Not to mention that sewage can monitor not only influenza but other pathogens,” added Alves.

Innovative vaccine

The IPSP project proposes creating a vaccine platform based on self-replicating RNA. This technology mimics a mechanism found in some viruses, such as chikungunya and other alphaviruses, in which the coding sequence of the introduced target vaccine protein is replicated multiple times by mechanisms inserted into the vaccine’s own RNA.

“Its advantage is that it requires a smaller amount of RNA and creates longer-lasting immune responses, which results in increased efficacy of the vaccine and reduced side effects. It also increases the speed at which the vaccine can be produced. Many current flu vaccines depend on the reproduction of eggs to obtain the virus vectors,” explained the biomedical scientist.

“This is a platform that I learned to master and was responsible for implementing during my four years of postdoctoral studies, completed in June of this year at the La Jolla Institute for Immunology, in San Diego, in the United States. There, I developed new vaccines against Covid-19, dengue, zika, among other flaviviruses, using this technology,” he said.

According to Alves, the biggest concern is with potentially pandemic subtypes: “Today it is with bird flu, type A, subtype H5N1. In the United States, an outbreak of the disease is occurring in cattle herds and the first cases in humans have already been identified. The virus has also been found to be circulating in sewage. Thus, the virus is causing spillover [transbordamento]contaminating other species besides birds. However, by carrying out efficient surveillance and developing more effective immunizers, we can prevent it from becoming a pandemic.”

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This content was originally published in Scientists monitor flu virus mutations in sewage samples on the CNN Brasil website.

Source: CNN Brasil

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