Rabies continues to present a public health threat in most countries of the world. B cells (Bmem) in the draining LNs and plasma cells (PCs) in the bone marrow (BM) for up to 360 days postimmunization (dpi). As a result of the presence of the long-lived PCs, it also generated prolonged virus-neutralizing antibodies (VNAs), resulting in better protection against a lethal challenge than that seen with rLBNSE. Moreover, consistent with the increased numbers of Bmem and PCs after a boost with rLBNSE, rLBNSE-IL-7-immunized mice promptly produced a more potent secondary anti-RABV neutralizing antibody response than rLBNSE-immunized mice. Overall, our data suggest that overexpressing IL-7 improved the induction of long-lasting primary and secondary antibody responses post-RABV immunization. IMPORTANCE Extending humoral immune responses using adjuvants is an important method to develop long-lasting and efficient vaccines against rabies. However, little information is currently available regarding prolonged immunological memory post-RABV vaccination. In this study, a novel rabies vaccine that expressed murine IL-7 was developed. This vaccine enhanced the numbers of Tfh cells and the GC responses, resulting in upregulated quantities of Bmem and PCs. Moreover, we found that the long-lived PCs that were elicited by the IL-7-expressing recombinant virus (rLBNSE-IL-7) were able to sustain VNA levels much longer than those 914458-22-3 elicited by the parent rLBNSE virus. Upon reexposure to the pathogen, the longevous Bmem, which maintained higher numbers for up to 360 914458-22-3 dpi with rLBNSE-IL-7 compared to rLBNSE, could differentiate into antibody-secreting cells, resulting in rapid and potent secondary production of VNAs. These results suggest that the expression of IL-7 is beneficial for induction of potent and 914458-22-3 long-lasting humoral immune responses. genus in the family. Rabies is a public health threat that causes more than 59,000 human deaths around the world each year, and most of these deaths occur in the developing countries of Asia and Africa (1, 2). Globally, over 3 billion humans are threatened with exposure to rabies because they live in areas where rabies is endemic in domestic or wild animals (3). More than 95% of human rabies cases are related to dog bites, indicating that it is critical to control rabies in domestic animals, especially dogs, in order to control and eliminate rabies in humans. The mass (>70%) vaccination of domestic dogs has nearly eliminated cases of human rabies in developed and some developing countries. However, 914458-22-3 the traditional inactivated animal vaccines induce protective antibody (Ab) responses only after multiple shots and generally require repeated booster doses to provide long-lasting protection in preexposure settings (4, 5), which increases the operational costs and restricts their wide use in developing countries. Therefore, there is still an urgent need to develop a single-dose and long-lasting RABV vaccine that can induce robust antibodies, especially virus-neutralizing antibodies (VNAs), to protect animals from rabies. Vaccines usually induce antibody responses via pathways that involve T cell-independent and T cell-dependent B cell mechanisms. An early study showed that antibodies produced in T cell-independent responses peaked at around 5 to 7 days postimmunization (dpi) and Mouse monoclonal to CD56.COC56 reacts with CD56, a 175-220 kDa Neural Cell Adhesion Molecule (NCAM), expressed on 10-25% of peripheral blood lymphocytes, including all CD16+ NK cells and approximately 5% of CD3+ lymphocytes, referred to as NKT cells. It also is present at brain and neuromuscular junctions, certain LGL leukemias, small cell lung carcinomas, neuronally derived tumors, myeloma and myeloid leukemias. CD56 (NCAM) is involved in neuronal homotypic cell adhesion which is implicated in neural development, and in cell differentiation during embryogenesis did not generate memory B cells (Bmem) with a replication-deficient RABV-based vaccine, suggesting that humoral immunity induced by cooperation between specialized populations of B cells and CD4+ T cells may hold the key to the development of a relatively prolonged antibody response (6). During the development of vaccine-induced humoral immunity, CD4+ T cells are primed by dendritic cells (DCs), are loaded with antigens in the T cell zone, and move toward the B cell follicles (7). When follicular B cells acquire antigen, they migrate toward the border of the T cell zone and further differentiate into short-lived plasma cells (PCs) and early Bmem or return to the follicle and undergo rapid proliferation to form a germinal center (GC) (8). Within the GCs, B cells acquire an antigen by synapsing with antigen-presenting cells such as DCs and macrophages and with specialized stromal cells known as follicular dendritic cells (FDCs) (9) and via contact with additional signals produced by T follicular helper (Tfh) cells (10, 11). GC B cells emigrate from the follicle and differentiate into long-lived PCs or Bmem (8). Humoral immune responses require long-lived PCs that produce copious amounts of antibodies capable of neutralizing pathogenic antigens over time (12). Long-lived Bmem renew antibody responses by rapidly differentiating into antibody-secreting cells upon reexposure to antigen (13). Interleukin-7 (IL-7) is definitely a nonhematopoietic, cell-derived 914458-22-3 cytokine that takes on a.