Isolation and sequence analysis of the complete VP2 gene of canine parvovirus from Chinese domestic pets and determination of the pathogenesis of these circulating strains in beagles

Canine parvovirus (CPV) causes acute gastroenteritis in domestic dogs, cats, and several wild carnivore species. In this study, the full-length VP2 gene of 36 CPV isolates from dogs and cats infected between 2016 and 2017 in Beijing was sequenced and analyzed. The results showed that, in dogs, the new CPV-2a strain was the predominant variant (n = 18; 50%), followed by the new CPV-2b (n = 6; 16.7%) and CPV-2c (n = 3; 8.3%) strains, whereas, among cats, the predominant strain was still CPV-2 (n = 9; 25%). One new CPV-2a strain, 20170320-BJ-11, and two CPV-2c strains, 20160810-BJ-81 and 20170322-BJ-26, were isolated and used to perform experimental infections. Multiple organs of beagles that died tested PCR positive for CPV, and characteristic histopathological lesions were observed in organs, including the liver, spleen, lungs, kidneys, small intestines, and lymph nodes. Experimental infections showed that the isolates from the epidemic caused high morbidity in beagles, indicating their virulence in animals and suggesting the need to further monitor evolution of CPV in China.

Phospholipase C signaling is involved in porcine reproductive and respiratory syndrome virus infection in cell cultures

The phospholipase C (PLC) is a family of kinases that hydrolyze phosphatidylinositol 4,5-bisphosphate [PI(4,5)P2] to generate two second messengers, inositol 1,4,5-trisphosphate (IP3) and diacylglycerol (DAG), which stimulate distinct downstream signaling. Recently, it has been reported that PLC signaling is activated by multiple viruses for efficient replication and the virus-induced inflammatory response. In this study, we demonstrated that PLC-specific inhibitor U73122 strongly suppressed porcine reproductive and respiratory syndrome virus (PRRSV) productive infection in cell cultures. The inhibitor affected both viral post-binding cell entry and post-entry processes. The virus infection led to an early transient activation of PLCγ-1 at 0.5 h post-infection (hpi), and sustained event at a stage from 4 to 16 hpi in MARC-145 cells. In addition, U73122 inhibited the activation of p38 MAPK signaling stimulated by PRRSV infection, suggesting that PLC signaling may be associated with the virus infection-induced inflammatory response. Taken together, these studies suggested that PLC signaling played an important role in PRRSV infection or pathogenesis. Keywords: PRRSV; U73122; phospholipase C; PLCγ-1.

PEGylated polycyanoacrylate nanoparticles as salvicine carriers: synthesis, preparation, and in vitro characterization

AIM

To synthesized poly(methoxypolyethyleneglycol cyanoacrylate-co-n-hexadecyl cyanoacrylate) (PEGylated PHDCA) with polyethylene glycol (PEG, Mr = 5000), prepare PEGylated PHDCA and poly(n-hexadecyl cyanoacrylate) (PHDCA) nanoparticles loading salvicine and determine their in vitro characterizations.

METHODS

The structure of PEGylated PHDCA was determined with 1H-NMR, 13C-NMR and Fourier transform infrared spectrum (FTIR). Its molecular weight was determined by gel permeation chromatography (GPC). Nanoparticles were prepared by emulsion/solvent evaporation method.

RESULTS

1H-NMR, 13C-NMR, and FTIR were consistent with structure of PEGylated PHDCA, whose average molecular weight is 6680. Entrapment efficiency could be determined by high pressure liquid chromatography (HPLC) method without endogenous interference at the retention time of salvicine. The entrapment efficiency was 92.6 % for PEGylated PHDCA nanoparticles and 98.9 % for PHDCA nanoparticles. The nanoparticles size was about 250 nm. The values of the zeta potential were obviously influenced by the composition of the copolymer. Compared with PHDCA nanoparticles (-23.1 mV), PEGylated PHDCA nanoparticles showed a low surface potential (-9.6 mV). Salvicine release from nanoparticles showed an initial burst effect, then a plateau for an extended period, and finally sustained release phase.

CONCLUSION

These results showed that the PEGylated PHDCA nanoparticles could be an effective carrier for salvicine delivery in the respect of anti-tumor potency.