Preparation of mouse anti-human rotavirus VP7 monoclonal antibody and its protective effect on rotavirus infection

Identification of a novel linear B-cell epitope recognized by a monoclonal antibody against the capsid protein of goose astrovirus genotypes 2

BACKGROUND

Goose astrovirus genotype 2 (GoAstV-2) is a novel and highly infectious pathogen characterized by symptoms of gout, swelling, and hemorrhage of the kidneys in 5-15-day-old goslings. The virus has caused severe economic losses for the goose husbandry industry. The capsid protein of GoAstV-2 is involved in viral packaging and immunogenicity, and it has served as a target antigen for diagnostic methods.

RESULTS

In this study, the N-terminus of the GoAstV-2 Cap protein (rCap) was successfully expressed and used to immunize BALB/c mice. A new monoclonal antibody (mAb) named 7B2 against the GoAstV-2 rCap protein was prepared. Immunofluorescence assay and Western blot analysis showed that mAb 7B2 had a strong binding affinity to the GoAstV-2 rCap protein. The results of epitope mapping demonstrated that the minimum linear epitope recognized by mAb 7B2 was located in the amino acids 153NTAGPESIDT162. Sequence homology analysis revealed that this epitope was highly conserved among the GoAstV-2 strains analyzed and that it showed 90% sequence similarity with turkey astrovirus 2 strains and low similarity (less than 50%) with other astroviruses.

CONCLUSIONS

These findings will be useful for the development of diagnostic kits for GoAstV-2 and will aid further research on the structure and function of the capsid protein.

Identificationof a novel linear epitope on the porcine reproductive and respiratory syndrome virus nucleocapsid protein, as recognized by a specific monoclonal antibody

Introduction

Porcine reproductive and respiratory syndrome virus (PRRSV) remains one of the most threatening pathogens of swine. The nucleocapsid (N) protein is the major structural protein of the virus and has been used as a PRRSV diagnostic antigen due to its high level of inherent immunogenicity.

Methods

The recombinant PRRSV N protein was generated by the prokaryotic expressing system and used to immunized mice. Monoclonal antibodies against PRRSV were produced and validated by western blot analysis and indirect immunofluorescence analysis. In this study, the linear epitope of a specific monoclonal antibody mAb (N06) was subsequently identified by enzyme-linked immunosorbent assays (ELISA) using the synthesized overlapping peptides as antigens.

Results

According to the results of western blot analysis and indirect immunofluorescence analysis, mAb (N06) was capable of recognizing the native form as well as the denatured form of PRRSV N protein. The results of ELISA showed that mAb N06 recognized the epitope NRKKNPEKPHFPLATE, which was consistent with BCPREDS predictions of antigenicity.

Conclusion

All the data suggested that the mAb (N06) can be used as diagnostic reagents for PRRSV detection, while the recognized linear epitope can be useful in epitope-based vaccines development, which is helpful for the control of local PRRSV infections in swine.

A Study on the Time-Effect and Dose-Effect Relationships of Polysaccharide from Opuntia dillenii against Cadmium-Induced Liver Injury in Mice

The purpose of this study was to evaluate the protective effect of Opuntia dillenii (Ker-Gaw) Haw. polysaccharide (ODP) against cadmium-induced liver injury. Cadmium chloride (CdCl2) was used to construct a mice evaluation model, and the indicators chosen included general signs, liver index, biochemical indicators, blood indicators, and pathological changes. A dose of 200 mg/kg ODP was applied to the mice exposed to cadmium for different lengths of time (7, 14, 21, 28, and 35 days). The results showed that CdCl2 intervention led to slow weight growth (reduced by 13−20%); liver enlargement; significantly increased aspartate aminotransferase (AST, 45.6−52.0%), alanine aminotransferase (ALT, 26.6−31.3%), and alkaline phosphatase (ALP, 38.2−43.1%) levels; and significantly decreased hemoglobin (HGB, 13.1−15.2%), mean corpuscular hemoglobin (MCH, 16.5−19.3%), and mean corpuscular hemoglobin concentrations (MCHC, 8.0−12.7%) (p < 0.01). In addition, it led to pathological features such as liver cell swelling, nuclear exposure, central venous congestion, apoptosis, and inflammatory cell infiltration. The onset of ODP anti-cadmium-induced liver injury occurred within 7 days after administration, and the efficacy reached the highest level after continuous administration for 14 days, a trend that could continue until 35 days. Different doses (50, 100, 200, 400, and 600 mg/kg) of ODP have a certain degree of protective effect on cadmium-induced liver injury, showing a good dose−effect relationship. After 28 days of administration of a 200 mg/kg dose, all pathological indicators were close to normal values. These findings indicated that ODP had positive activity against cadmium-induced liver injury and excellent potential for use as a health food or therapeutic drug.