A recent study finds that administering IgA antibodies via nasal spray can fend off multiple omicron variants within the respiratory tract.
As the COVID-19 virus continues to mutate, people are eager to find an effective way to prevent infection. A recent study finds that administering IgA antibodies via nasal spray can fend off multiple omicron variants within the respiratory tract.
The immune system generates different types of antibodies, each serving distinct functions. IgA antibodies in the respiratory mucosa play a protective role at the entry point of viruses in the respiratory tract, preventing their replication or entry into the lungs. The COVID-19 vaccines primarily stimulate an IgG antibody response within the body, with limited impact on the induction of mucosal IgA antibodies. The preventive capability of IgG antibodies generated via vaccination with the original strain is also less effective against the omicron variant.
In January, a study from
Sweden’s Karolinska Institutet was published in the Proceedings of the National Academy of Sciences (PNAS). In it, researchers used genetic engineering to convert IgG antibodies into IgA antibodies, and the results revealed that these exhibited a more robust neutralizing activity against the omicron variant. For the omicron subvariants BA.1, BA.2, BA.4, and BA.5, the potency of IgA antibodies increased by 25 to 75 times compared to the parental IgG antibodies.
The researchers treated mice infected with the omicron variant by administering IgA antibodies intranasally. The results revealed that the nasal spray significantly reduced the viral load in the mice’s trachea and lungs. Compared to the parental IgG antibodies, IgA antibodies exhibited a stronger binding capacity to the spike protein of the SARS-CoV-2, the virus responsible for causing COVID-19, resulting in a more effective neutralization of the virus.
An
earlier study found that IgA antibodies produced in the respiratory mucosa, whether through infection with the original COVID-19 virus or vaccination targeting it, can effectively prevent omicron variant infection. The higher the levels of IgA antibodies in saliva, the less susceptible individuals are to the omicron variant. Conversely, even after a person receives the COVID-19 vaccine, a lack of IgA antibodies still poses a higher risk of contracting COVID-19.
The research team indicated that the IgA antibodies in the nasal spray are expected to provide at least 24 hours of protection, and they aim to develop nasal sprays with even longer-lasting protection in the future. The researchers believe this IgA antibody nasal spray can be used for both preventive measures and post-infection treatment. Direct supplementation of IgA antibodies via nasal spray is particularly beneficial for people with compromised immune systems, such as those with HIV/AIDS, who may not generate sufficient immunity through vaccination.
Active vs. Passive Immunity
Harold Marcotte, an associate professor from the Department of Medical Biochemistry and Biophysics at the Karolinska Institutet and the first author of the paper, stated in a press release that vaccines can trigger the body’s active immune response, whereas IgA antibody nasal sprays represent a passive immunization strategy.Active immune response refers to the immune system generating antibodies on its own to eliminate viruses, while passive immune response involves directly supplementing antibodies to acquire corresponding protection.
Mr. Marcotte added, “An active immunization approach that induces a mucosal immune response would be ideal, but hopefully our approach is suitable for protecting the most vulnerable individuals, like the elderly or immunocompromised persons.”
Qiang Pan-Hammarström, the study’s corresponding author, stated that this strategy holds great promise, not only for COVID-19 and its new variants but also for other infectious diseases like influenza and Helicobacter pylori (for which there is currently no vaccine).
Mucosa serves as the first line of defense against viral invasion. Numerous research teams are dedicated to developing nasal spray medications to enhance mucosal defense against viruses. An
animal study published in Nature in 2022 revealed that a molecule called N-0385 can prevent the entry of the COVID-19 virus into cells. Administering this molecule shortly after infection could potentially serve as an early treatment option.
The researchers tested this treatment method on mice with human virus receptors on their cells. They introduced N-0385 into the mice through nasal administration at different stages: before, during, and after infection. By measuring indicators such as weight and temperature, the researchers found that this drug could prevent the onset of illness in mice. Additionally, the drug reduced mortality rates for mice infected with the virus. Even when administered 12 hours after infection, it exhibited remarkable therapeutic efficacy.
Other Nasal Sprays in Development
1. Xylitol Nasal Spray
Xylitol is a natural, low-calorie sweetener known for its antibacterial and antiviral properties.
In vitro experiments have demonstrated that the components of xylitol nasal spray play a role in reducing viral load and preventing viral infection in cells.
2. Iota-Carrageenan Nasal Spray
Iota-carrageenan is a polysaccharide extracted from red algae, commonly used as a gelling agent in puddings or ice cream.
A study involving 400 hospital workers in Argentina suggested that nasal spray containing iota-carrageenan may reduce the risk of contracting COVID-19 by 80 percent.
3. Nitric Oxide Nasal Spray
Nitric oxide nasal spray has been found to help prevent severe illness caused by the COVID-19 virus. A
small-scale study indicated that the spray could reduce viral load by approximately 95 percent within 24 hours and 99 percent within 72 hours.
A
randomized controlled trial involving mild-infection COVID-19 patients found that nitric oxide nasal spray can accelerate virus clearance. Patients receiving the nasal spray tested negative approximately four days sooner than those in the control group.
Scientists are also developing intranasal booster vaccines to enhance mucosal immune responses. In July 2023, the Icahn School of Medicine at Mount Sinai in New York
announced that CastleVax has completed phase 1 trials for its nasal vaccine.
The study is expected to be completed in the spring of 2024.
