The research team also examined the patients' antibody titers to the two influenza A virus strains and distribution of circulating B cell subsets. The team also analyzed the participants' blood transcriptome and expression of immunoregulatory markers on B cells at baseline after vaccination. The experts found that African Americans exhibited higher virus neutralizing and IgG antibody responses to two flu virus strains compared with Caucasians. The study also revealed that patients of African American descent displayed higher levels of circulating B cell subsets than their Caucasian counterparts. However, the research team found that the effects diminished with age among African American patients.
The findings were published in the journal Oncotarget.
A previous research published in 2016 had also identified a race-dependent immune response to flu vaccine. To assess this, researchers at the Dana-Farber Cancer Institute focused on variations of the IGHV1-69 gene. According to the research team, this antibody was one of about 50 human genes responsible for developing millions of protein antibodies that fend off infection. Researchers said IGHV1-69 gene patrolled the body and distinguished molecules located on the surface of virus. The antibodies then prompted neutralizing antibodies to inhibit the infection.
According to the researchers, antibodies produced by IGHV1-69 gene showed potential in developing universal flu vaccines, as these antibodies bound to the stem of hemagglutinin, a lollipop-shaped protein located on the flu virus' surface. However, the research team noted that some versions of the gene were more effective than others in responding to flu virus. The experts noted that 15 to 20 percent of people do not carry the effective variations of the gene, prompting manufacturers to use some other genes that were otherwise not fully recognized. This could be a reason why current flu vaccines do not show a 100 percent efficacy, the study's lead researcher said.
As part of the study, the experts examined stored blood samples taken from patients vaccinated against the H5N1 flu virus in 2007. The research team found that flu virus response differed from one participants to another depending on the genetic version they carried. The immune response was also dependent on the number of genetic copies present. In addition, the researchers found that the frequency of IGHV1-69 gene variants were significantly different between three ethnic groups: African, Asian, and European.
The findings suggested that health experts should develop a complete catalog of antibody variants including the IGHV1-69 gene, and map them according to certain populations worldwide. The researchers also stressed that doing so will be an important step in the development and monitoring of the next-generation flu vaccines designed to target the hemagglutinin stem region.
"I think the fact that you have different ethnic backgrounds based on their genetic variation either responding well or not responding well to the flu virus vaccine is of potential huge significance. The fact that it's only one gene is quite promising, because that will potentially make it easier to implement it clinically," said outside expert Dr. Ronald Cohn in an article in CBC.ca.
The findings were published in the journal Scientific Reports.