ABSTRACT
Objective To evaluate the immune effects of virus-like particles ( VLPs) assembled from the capsid protein VP1 of a recombinant norovirus ( NoV) GⅡ. 17 genotype. Methods The recombi-nant NoV GⅡ. 17 VP1 VLPs were purified, and then tested by SDS-PAGE and Western blot to analyze the purity. The size, morphology and diameter distribution of the recombinant VLPs were detected by transmis-sion electron microscopy ( TEM) and dynamic light scattering ( DLS) analyzer. The recombinant VP1 VLPs adsorbed by aluminium adjuvant were used to immunize BALB/c mice. Serum samples were collected after immunization. Specific antibody level and neutralizing antibody activity were evaluated with enzyme linked immunosorbent assay ( ELISA) and histo-blood group antigen ( HBGA)-VLP blocking test. Cross-reactivity of serum samples with GⅠ. 1 and GⅡ. 4 VP1 VLPs were detected. Moreover, cross-protection against GⅠ. 1 and GⅡ. 4 VP1 VLPs was analyzed. Results The purity of the recombinant NoV GⅡ. 17 VP1 VLP was greater than 90％ and specific bands were detected by Western blot. TEM images and DLS experiments showed that VLPs were 30-50 nm in size with good morphology and uniformity, indicating that the recombi-nant VLPs were similar to the wildtype virus. High titers of specific antibodies were detected in serum sam-ples of the immunized mice. A certain degree of cross-reactions between serum samples and VP1 VLPs of NoV GⅠ. 1 and GⅡ. 4 were observed, but no cross-protection was detected. Conclusion The recombinant GⅡ. 17 VP1 VLPs in combination with aluminum adjuvant can induce higher titers of HBGA blocking anti-bodies in mice, suggesting that it could be used as a candidate target antigen for norovirus vaccine.
ABSTRACT
Objective To investigate the prevalent situations of norovirus infection and genotype distributions in 2014 in Suzhou area .Methods A total of 322 fecal specimens were collected from infants with suspected viral diarrhea at Children′s Hospital of Soochow University in 2014 .Norovirus genogroupⅠ and Ⅱ was detected by reverse transcription (RT )‐polymerase chain reaction (PCR) ,In an effort to identify norovirus genotypes , RNA dependent RNA polymerase region (region A ) and capsid region (region C) segment of some samples positive for norovirus was amplified by RT‐PCR .Comprehensive molecular characteristics of norovirus were obtained by sequence analysis of the same samples in different regions .Results Among 322 fecal specimens ,67 cases were positive for norovirus of G Ⅱ group ,and norovirus of GⅠ group was not found .The genetic fragments of region A was successfully detected in 42 strains .Among all 42 specimens ,there were 35 GⅡ .e strains ,3 GⅡ .7 strains ,2 GⅡ .17 strains and 2 GⅡ .12 strains .The genetic fragments of region C was successfully detected in 53 strains .Among these 53 specimens ,there were 44 GⅡ .4‐2012Sydney strains ,4 GⅡ .6 strains ,2 GⅡ .17 strains ,2 GⅡ .3 strains and 1 GⅡ .2 strain .Conclusions It′s indicated that G Ⅱ .4‐2012Sydney is the main genotype of norovirus causing viral diarrhea in Suzhou ,and other genotypes including the new GⅡ .17 variant ,GⅡ . 7/GⅡ .6 and GⅡ .12/GⅡ .3 recombinant strains also exist .