Search

Sericin, a silk-derived non-immunogenic protein, has been used to improve cell culture performance by increasing viability, cell concentration, and promoting adherence of several cell lines. Here, we hypothesized that the properties of sericin can enhance the amplification of flaviviruses in cell cultures. The propagation of flavivirus is inefficient and limits scientific research. Zika virus (ZIKV) is an important human pathogen that has been widely studied because of its high impact on public health. There is a need to amplify Zika virus both for research and vaccine development. In this work, we show that sericin improves ZIKV amplification in insect (C6/36) and mammalian (Vero) cell cultures, and that it has a cryoprotectant capacity. Supplementation of cell culture media with sericin at 80 µg/mL resulted in a significant increase of 1 log in the concentration of ZIKV infectious particles produced from both cell lines. Furthermore, final virus yields increased between 5 and 10-fold in Vero cells and between 7 and 23-fold in C6/36 cells when sericin was supplemented, compared to control conditions. These results show that sericin is an effective supplement to increase ZIKV production by Vero and C6/36 cells. Additionally, sericin was a suitable cryoprotective agent, and hence an alternative to FBS and DMSO, for the cryopreservation of C6/36 cells but not for Vero cells.

Porcine enteric sapovirus (PES) has been shown to cause diarrhea under experimental conditions in gnotobiotic piglets. However, the role of PES as enteric pathogens in porcine farms remains unclear. To further understand the PES-host interactions under field conditions, a serological survey was carried out. To this end the capsid gene of a PES isolate was cloned in the baculovirus expression system and an ELISA was developed based on virus-like particles from the baculovirus-expressed PES capsid protein. A total of 85 serum samples collected from pigs ranging from 8 weeks to over 54 weeks of age were analyzed. An overall seroprevalence to PESs of 62% was found, with significant differences (p0.05) found between ages. Pigs younger than 10 weeks old and older than 12 weeks old showed high seroprevalences (70-100%), while pigs aged 10-12 weeks showed no detectable serum antibodies levels. Our results suggest that PES infections are common in pigs and that passively acquired maternal antibodies are soon replaced by actively acquired antibodies, whose titers increase gradually with age and that probably are maintained during lifetime.