Policy statement of enteral nutrition for preterm and very low birthweight infants.

For preterm and very low birthweight infants, the mother's own milk is the best nutrition. Based on the latest information for mothers who give birth to preterm and very low birthweight infants, medical staff should encourage and assist mothers to pump or express and provide their own milk whenever possible. If the supply of maternal milk is insufficient even though they receive adequate support, or the mother's own milk cannot be given to her infant for any reason, donor human milk should be used. Donors who donate their breast milk need to meet the Guideline of the Japan Human Milk Bank Association. Donor human milk should be provided according to the medical needs of preterm and very low birthweight infants, regardless of their family's financial status. In the future, it will be necessary to create a system to supply an exclusive human milk-based diet (EHMD), consisting of human milk with the addition of a human milk-derived human milk fortifier, to preterm and very low birthweight infants.

Construction and application of chimeric virus-like particles of tick-borne encephalitis virus and mosquito-borne Japanese encephalitis virus.

We have previously reported a system for packaging tick-borne encephalitis (TBE) virus subgenomic replicon RNAs into single-round infectious virus-like particles (VLPs) by using in trans expression of viral C/prM/E structural proteins. In this study, the trans-packaging system was applied to the generation of chimeric VLPs with mosquito-borne Japanese encephalitis (JE) virus. Although trans-expression of TBE virus C and JE virus prM/E proteins resulted in the secretion of VLPs, the expression of JE virus C/prM/E proteins did not lead to the secretion of VLPs, suggesting that homologous interaction between C and non-structural proteins or the genomic RNA is important for efficient assembly of infectious particles. Neutralization testing showed that the antigenic characteristics of the VLPs were similar to those of the native virus. Furthermore, the infectivities of the TBE virus- and JE virus-enveloped VLPs for the ISE6 tick cell line and C6/36 mosquito cell line were investigated. The VLPs were able to enter only those cells that were derived from the natural vectors for the respective viruses. TBE virus replicon RNA packaged in VLPs produced TBE virus non-structural proteins in tick cells, but could neither replicate nor produce viral proteins in mosquito cells. These findings indicate the importance of specific cellular factors for virus entry and replication during flavivirus infection of arthropods. These results demonstrate that chimeric VLPs are useful tools for the study of viral genome packaging and cellular factors involved in vector specificity, with the additional safety aspect that these chimeric VLPs can be used instead of full-length chimeric viruses.

Packaging the replicon RNA of the Far-Eastern subtype of tick-borne encephalitis virus into single-round infectious particles: development of a heterologous gene delivery system.

The sub-genomic replicon of tick-borne encephalitis (TBE) virus (Far-Eastern subtype) was packaged into infectious particles by providing the viral structural proteins in trans. Sequential transfection of TBE replicon RNA and a plasmid that expressed the structural proteins led to the secretion of infectious particles that contained TBE replicon RNA. The secreted particles had single-round infectivity, which was inhibited by TBE virus-neutralizing antibody. The physical structure of the particles was almost identical to that of infectious virions, and the packaged replicon RNA showed no recombination with the mRNAs of the viral structural proteins. Furthermore, heterologous genes were successfully delivered and expressed by packaging TBE replicon RNA with inserted GFP and Neo genes. This replicon packaging system may be a useful tool for the molecular study of the TBE virus genome packaging mechanism, and for the development of vaccine delivery systems.