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Utilizing subunit vaccines is one of the strategies to address influenza infection. Recent innovations have focused on high doses of vaccine antigens and immune enhancers or adjuvant to induce more robust and long-lasting immune responses. Here, an effect of the B cell-activating factor receptor (BAFF-R) to increase the magnitude and durability of immune responses of the recombinant HA1 (rHA1) protein against the H1N1 influenza virus was studied. The HA1 protein and the effector domain of BAFF-R were expressed in the pET-28a (+) vector. Eight-week-old BALB/c mice were equally grouped into five groups (n=20). The 15 and 25 μg/μL of rHA1 were mixed with 2 μg/μL of rBAFF-R and injected three times for vaccinated groups. Three control groups were received normal saline and two concentrations of rHA1. The ability of rBAFF-R in eliciting HA-specific antibody response and stimulating T lymphocyte proliferation to induce the cell-mediated immunity was assayed. Induction of protection was evaluated following the challenge with PR8 strain. Analysis of immune responses showed that the co-administration of rBAFF-R with rHA1 boosted HI responses to the antigen in mice, whilst it was not able to promote the T cell proliferation responses against influenza. Compared to rHA1alone, the rBAFF-R/rHA1 generated efficient protection for the animals. There were no significant differences in eliciting the immune responses in mice immunized with the lower dose of rHA1 than that with the higher dose. The data indicate the rBAFF-R can enhance the primary and memory immune responses to protect against influenza infection. [ABSTRACT FROM AUTHOR]

Background: In the last decade due to emerge and remerge of influenza viruses, quality improvement of vaccines to increase immune responses in target populations have been more necessary. The potential of biologic adjuvant to stimulate and induce immune system is the basis of modern researches in prevention and controlling program of infectious diseases. In this study, the effect of the coding sequence of cellular Myxovirus resistance (Mx) protein as a biological adjuvant for inducing humoral immune response against influenza virus was investigated. Methods: The experimental study was performed on Balb/c mice in Razi Vaccine and Serum Research Institute from June to November 2014. Three conserved motifs of Mx were selected following sequence alignment between human, mouse and bird species. Potential of the motifs for stimulation immune responses against influenza virus were evaluated using in silico analysis. Based on the immune informatics data Mx1 sequence was the best immune inducer and cloned into pcDNA3.1 vector. Then formulated with inactivated H9N2 influenza antigen as adjuvant and injected to mice groups. The sera of vaccinated mice were collected prior to priming and boosting injections and also at defined weeks and analyzed with serological assays. Histopathological examination was done for evaluation of the vaccine and adjuvant safety. Results: The mean weight of the Balb/c mice in all control and treatment groups was similar and ranged from 21 to 37 gr (P= 0.05). The difference in increasing antibody titers against influenza virus in immunized mice who received Mx1-adjuvanted vaccine especially in second boosting was significant (P= 0.01) compared to the vaccine alone group. More than 78% of the immunized mice receiving two-time boosting have the mean antibody titer of >6 (Log2) which was higher (P= 0.001) comparing to the mice with one booster injection. Conclusion: These data revealed that Mx1 as biological adjuvant was able to increase antibody titer and induction memory immune responses against influenza immunization without causing any side effects. [ABSTRACT FROM AUTHOR]

Utilizing subunit vaccines is one of the strategies to address influenza infection. Recent innovations have focused on high doses of vaccine antigens and immune enhancers or adjuvant to induce more robust and long-lasting immune responses. Here, an effect of the B cell-activating factor receptor (BAFF-R) to increase the magnitude and durability of immune responses of the recombinant HA1 (rHA1) protein against the H1N1 influenza virus was studied. The HA1 protein and the effector domain of BAFF-R were expressed in the pET-28a (+) vector. Eight-week-old BALB/c mice were equally grouped into five groups (n=20). The 15 and 25 μg/μL of rHA1 were mixed with 2 μg/μL of rBAFF-R and injected three times for vaccinated groups. Three control groups were received normal saline and two concentrations of rHA1. The ability of rBAFF-R in eliciting HA-specific antibody response and stimulating T lymphocyte proliferation to induce the cell-mediated immunity was assayed. Induction of protection was evaluated following the challenge with PR8 strain. Analysis of immune responses showed that the co-administration of rBAFF-R with rHA1 boosted HI responses to the antigen in mice, whilst it was not able to promote the T cell proliferation responses against influenza. Compared to rHA1alone, the rBAFF-R/rHA1 generated efficient protection for the animals. There were no significant differences in eliciting the immune responses in mice immunized with the lower dose of rHA1 than that with the higher dose. The data indicate the rBAFF-R can enhance the primary and memory immune responses to protect against influenza infection.