Nanotechnology-based compound used to deliver the vaccine against hepatitis B

Compounds based on nanotechnologies are currently being tested as a possible delivery vector for vaccines. A team of researchers has demonstrated how the SBA-15 oral delivery vehicle, a nanotechnology-based compound of this type, can deliver an oral vaccine against hepatitis B to the immune system.

Researchers from Brazil and Europe have shown that the nanotechnology-based delivery system, composed of particles containing silica, and HBsAg, the hepatitis B surface antigen, reach the intestines without be destroyed by the acidity of the stomach. The study could pave the way for the development of new vaccines and new safe and non-invasive modes of administration.

The vaccine against hepatitis

Oral administration of antigens for vaccination purposes is an attractive idea for scientists, mainly because they are non-invasive, safe and pain-free in infants. In addition, oral delivery is cost-effective, making it a good proposition for immunization.

However, the development of a technology that allows oral vaccines to be effective remains a very difficult undertaking because many problems need to be solved. First of all, the vaccine must be administered in the intestines without being altered or damaged by the acids contained in the stomach. The main objective is to ensure that the administration system is resistant to the harsh conditions of the gastrointestinal tract.

Hepatitis B is a vaccine that helps protect the body against hepatitis B, caused by a virus. This can lead to inflammation of the liver and, in the long run, scarring of the organ, liver failure and cancer. The virus can be contracted by exposure to blood, sperm and other body fluids. A mother can also transmit the virus to her children during pregnancy.

The vaccine against hepatitis B is usually given by intramuscular injection at birth, at least one month after the first shot and at least two months after the second shot. Booster doses are given every five years.

Delivery system based on nanotechnology

The study, published in the journal Scientific reports and supported by the São Paulo Research Foundation – FAPESP and European research funders, shows how a viable, oral formulation of hepatitis B in the SBA-15 nanostructure silica, may constitute a mode effective administration of the oral vaccine.

Scientists from the Institute of Physics of the University of São Paulo (IF-USP) in Brazil have developed nanostructured silica and the Butantan Institute has developed the oral antigen. Silica and SBA-15 antigen have been subjected to various types of X-ray imaging in European laboratories.

To better understand the results, the researchers investigated how a 22 nanometer antigen, of a size of 22 nanometers, bound to silica nanotubes of about 10 nanometers in diameter and endowed with a bee nest structure. A nanometer, abbreviated to 1 nm, corresponds to one billionth of a meter.

Examinations revealed that the silica nanotubes and the antigen were measured by small angle X-ray scattering (SAXS), a transmission electron microscope and dynamic light scattering (DLS).

"Despite the difference in size, the tests [in animals] has produced an excellent immune response to the oral vaccine, as effective as the injectable form, "said Márcia Fantini, co-author of the study and professor at the IF-USP.

The 3D images collected by the various techniques have shown that even if the antigen does not enter the nanotubes, it remains in the macropores of 50 nm between the nanotubes, which means that the antigen is protected from the acids of the nanotubes. stomach.

Therefore, researchers now know the ideal ratio of the two compounds, so that the antigen is not agglomerated, preventing it from dispersing the active antigen in the intestine .

"In conclusion, the results obtained with the HBsAg encapsulated antigen are the first to demonstrate how SBA-15 protects the antigen during oral administration of the vaccine against hepatitis B. The vaccines encapsulated combine the benefits of vaccination with the ease of oral administration and concomitant induction of the immune response, "concluded the researchers.

Scientists plan to test polymers capable of covering the entire structure. In this way, the resistance of the antigen to the acidity of the human stomach can be enhanced and increased.

At the same time, some scientists led by Bordalo, Sant'Anna and Fantini are developing new antigens to add to the compound. Thus, in addition to hepatitis B, they plan to add other antigens, such as antigens against diphtheria and tetanus.

In addition, they plan to formulate a multi-vaccine that could also help immunize people against polio, whooping cough and Haemophilus influenzae type B (Hib), a vaccine that protects people against pneumonia and meningitis.