DNA vaccination against a fish rhabdovirus promotes an early chemokine-related recruitment of B cells to the muscle

Abstract

a b s t r a c tIn fish, intramuscular (i.m) injection of plasmid DNA encoding viral proteins has proved a highly effective vaccination strategy against some viral pathogens. The efficacy of DNA vaccination in teleost fish is based on the high level of viral antigen expression in muscle cells inducing a strong and long-lasting protection. However, the mechanisms through which this protection is established and effectuated in fish are still not fully understood. Moreover, similarities to mammalian models cannot be established since DNA vaccination in mammals usually induces much weaker responses. In this work, we have focused on the characterization of the immune cells that infiltrate the muscle at the site of DNA injection in vaccinated fish and the chemokines and chemokine receptors that may be involved in their infiltration. We have demonstrated through diverse techniques that B lymphocytes, both IgM + and IgT + cells, represented a major infiltrating cell type in fish vaccinated with a viral haemorrhagic septicaemia virus (VHSV) glycoprotein-encoding DNA vaccine, whereas in control fish injected with an oil adjuvant mainly granulocyte/monocyte-type cells were attracted. Among twelve chemokine genes studied, only CXCL11 L1, CK5B and CK6 mRNA levels were up-regulated in DNA vaccinated fish compared to fish injected with the corresponding vector backbone. Furthermore, the transcription of CXCR3B, a possible receptor for CXCL11 L1 was also significantly up-regulated in vaccinated fish. Finally, experiments performed with recombinant trout CK5B and CK6 and chemokine expression plasmids revealed that these chemokines have chemotactic capacities which might explain the recruitment of B cells to the site of DNA injection. Altogether, our results reveal that there is an early chemokine-related B cell recruitment triggered by i.m. DNA vaccination against VHSV which might play an important role in the initial phase of the immune response.

Molecular characterization and expression analysis of three subclasses of IgT in rainbow trout (Oncorhynchus mykiss)

“…Trout IgT2 was primarily expressed in the systemic lymphoid organs, like zebrafish IgZ1. This phenomenon may suggest the functional difference between these two IgT subclasses as well as the non-mucosal role for IgT (Castro et al, 2013, 2014; Castro and Tafalla, 2015). In addition, combined with the previous studies about trout IgT + B cells in various mucosal tissues during homeostatic conditions (Xu et al, 2013, 2016; Zhang et al, 2011), it seems that there are more IgT + B cells and IgT transcripts in gill than gut and skin.…”

“…IgT plays important roles in mucosal immunity in the gut (Zhang et al, 2010), skin (Xu et al, 2013) and gill (Xu et al, 2016) in rainbow trout ( Oncorhynchus mykiss ). In addition, recent studies indicated that IgT + B cells also participate in the responses against viral infections (Castro et al, 2013) and DNA vaccination (Castro et al, 2014). These evidences indicate that teleost IgT is also involved in systemic immunity (Castro and Tafalla, 2015).…”

Characterization of BAFF and APRIL subfamily receptors in rainbow trout (Oncorhynchus mykiss). Potential role of the BAFF / APRIL axis in the pathogenesis of proliferative kidney disease

“…DNase I-treated total RNA was prepared from tissue samples using a combination of Trizol (Invitrogen) and an RNAeasy Mini kit (Qiagen) as described previously [32]. Total RNA was eluted from the columns in RNase-free water, quantified using a Nanodrop 1000 spectrophotometer (Thermo Scientific) and stored at -80°C.…”

Intramuscular vaccination of Atlantic lumpfish (Cyclopterus lumpus L.) induces inflammatory reactions and local immunoglobulin M production at the vaccine administration site

“…However, no further characterization of the lymphocytes registered in these studies was reported. In addition, the type of vaccine used for injection might also be of significance, as reported by Castro et al (), where intramuscularly immunized rainbow trout ( Oncorhynchus mykiss L.) showed early recruitment of high levels of B lymphocytes (both IgM + and IgT + ) into the muscle, when injected with a DNA vaccine against VHSV, while fish injected with complete Freund's adjuvant mainly showed infiltration of granulocyte‐/monocyte‐type cells. Our results are in agreement with several of these authors’ observations, although it is uncertain whether the amount of IgM + cells would remain stable or increase/decrease as the inflammation progressed further beyond the time range of this study.…”