Truncated VP28 as oral vaccine candidate against WSSV infection in shrimp: an uptake and processing study in the midgut of Penaeus monodon

TLDR: The nearly identical uptake pattern of the different WSSV-antigens suggests that receptors on the apical membrane of shrimp enterocytes recognize rec-VP28 efficiently, and the truncated VP28 can be considered suitable for oral vaccination, when the digestion in the foregut can be bypassed.

About: This article is published in Fish & Shellfish Immunology.The article was published on 2013-01-01 and is currently open access. It has received 27 citations till now. The article focuses on the topics: Penaeus monodon & Apical membrane.

Figures

Fig. 1. Illustration of shrimp digestive tract, modified from Dall [24], showing stomach e S; midgut trunk e M; hindgut e H. Localization of WSSV-antigens in the lumen, its uptake/processing and associated haemocyte reaction are indicated by the shaded region that was observed in the proximal part of midgut from 2 hpi to 8 hpi (A); and in the median midgut along with the distal midgut from 24 hpi to 72 hpi (B). This figure is based on microscopical observations.

Table 1 Time-course ranking of VP28/immunoreactivity during processing of WSSVantigens in the median midgut.

Fig. 3. Histological sections of midgut from P. monodon intubated with IVP and WSSV. VP28 antigenic determinants and haemocytes are stained with anti-VP28 antibody (red) and WSH8 antibody (blue stained haemocytes), respectively. Both IVP (A: arrow) and WSSV (D: arrow) adhered to microvilli borders of epithelial cells at 2 and 4 hpi around proximal midgut. The presence of IVP in SNVs (B: arrow) at 8 hpi around median midgut was observed. IVP (C: red stain) transported in the inter-cellular space at 2 hpi near proximal midgut and WSSV (E: red stain) at 8 hpi near median midgut is also presented. Later on IVP (C: arrow) and WSSV (E: arrow) accumulated in the connective tissues is also represented. The exit of IVP and WSSV from the gut is also shown in B and E (arrow heads), respectively. The non-degranulated haemocytes (F: arrow) with its granules intact and degranulating haemocytes with diffused granules at 8 hpi (F: arrow head) is shown in IVP intubated median midgut. Massive degranulation (G) at 24 hpi observed as blue stain in the connective tissues of shrimps intubated with WSSV was observed near median midgut region. PBS intubated shrimp gut section indicating positive immunoreactivity for only the WSH8 antibody (H: arrow) is presented along with a section of median midgut of shrimp intubated with IVP subjected to immunohistochemistry excluding the mix of primary antibodies (I) at 24 hpi. Brush borders on the apical membrane (b), entire epithelial cell (e) and connective tissues (c) underlying the epithelium are indicated in all the figures from A to I.

Fig. 2. Histological sections of midgut from P. monodon intubated with rec-VP28. VP28 antigenic determinants and haemocytes are stained with anti-VP28 antibody (red) and WSH8 antibody (blue stained haemocytes), respectively. VP28 adhering to microvilli borders of proximal midgut epithelial cells at 2 hpi (A: arrow), enclosed in SNVs at 8 hpi in median midgut (B: arrow), within the inter-cellular space at 2 hpi around proximal midgut (C: red stain), accumulated in the connective tissue at 24 hpi near median midgut (E: arrow), exiting the gut at 24 hpi around proximal midgut (F: arrow) are presented. A parallel for the gut section of shrimp presented in (C) was subjected to immunohistochemistry excluding the mix of primary antibodies (D) to confirm the absence of background staining and internal peroxidase activity. Brush borders on the apical membrane (b), entire epithelial cell (e) and connective tissues (c) underlying the epithelium are indicated in all the figures from A to F.