The Virosome as a Novel Concept for High Pathogenic Porcine Reproductive and Respiratory Syndrome Virus (HP-PRRSV) Vaccines

Porcine reproductive and respiratory syndrome virus （PRRSV） is an envelope, positive, single-strand RNA virus and is a member of the Arteriviridae family, Nidovirales order. PRRSV is the viral pathogen responsible for porcine reproductive and respiratory syndrome （PRRS） and caused reproductive failure and high rate of late abortion and early farrowing in sows and respiratory disease in all age. In 2006, a large scale outbreak of atypical PRRS occurred in China is characterized by high fever （41-42℃）, high morbidity （50-100%） and high mortality （20-100%）. The disease was caused by a highly pathogenic PRRSV with a 30 amino acid deletions in its Nsp2 coding region. Because the PRRSV strains are genetically heterogeneous, and elicit delayed and weak cell-mediated immune （CMI） and antibody responses after vaccination the current vaccines are failed to provide sustainable disease control. Virosomes are virus-like particles, consisting of reconstituted virus envelopes without genetic material of the native virus. Since the virosomes has being similar to the original virus in terms of morphology and cell entry characteristics. Virosomes provide a vaccine platform that has the capacity to combine the antigen and an adjuvant within a single particle that could activate both the humoral and the cellular arm of the immune system. Furthermore, the virosomes are also providing a novel promising approach for the development of an efficacious vaccine against HP-PRRSV.

Enhanced mechanical properties of linear segmented shape memory poly（urethane-urea） by incorporating flexible PEG400 and rigid piperazine

The goal of this study is to design and synthesize a linear segmented shape memory poly（urethane-urea） （SMPUU） that possesses near-body-temperature shape memory temperature （Ttran） and enhanced mechanical properties by incorporating flexible poly（ethylene glycol） 400 （PEG400） to form poly（D,L-lactic acid）-based macro- diols （PDLLA-PEG400-PDLLA） and then rigid piperazine （PPZ） as a chain extender to form the desired SMPUUs （PEG400-PUU-PPZ）. PEG400 increased Mn while maintaining a lower Tg of PDLLA-PEG400-PDLLA, which together with PPZ improved the mechanical properties of PEG400-PUU-PPZ. The obtained optimum SMPUU with enhanced mechanical properties （O＇y = 24.28 MPa; zf = 698%; Uf = 181.5 MJIm3） and a Tg of 40.62~C exhibited sound shape memory properties as well, suggesting a promising SMPUU for in vivo biomedical applications.

Design,synthesis and characterization of novel poly(urethane-urea) based on a macrodiol from poly(lactic acid) and poly(p-dioxanone)

A series of novel poly（urethane-urea）（PUU） was synthesized from poly（lactide-co-p-dioxanone） macrodiol（HO-P（LA-co-PDO）-OH）, hexamethylene diisocyanate（HDI） and butanediamine（BDA）.The obtained PUU,which is recorded as P（LA-co-PDO）-PUU here,may demonstrate enhanced phase separation and thus improved shape memory property.FTIR was employed to characterize the copolymers,and the effects of NCO/OH molar ratios on Tg of PUU was investigated by means of differential scanning calorimetry （DSC）.The results revealed the successful synthesis of P（LA-co-PDO）-PUU.In addition,the Tg of P（LA-co-PDO）-PUU increased from 37.9℃to 44.2℃with the increase NCO/OH ratios from 1.1 to 1.2.The P（LA-co-PDO）-PUU with Tg close to body temperature will have potential applications as shape memory polymers in biomedical fields,especially in minimally invasive surgery.

A novel positively thermo-sensitive hydrogel based on ethylenediaminetetraacetic dianhydride and piperazine:Design,synthesis and characterization

A new positively thermo-sensitive hydrogel was designed and synthesized by a condensation polymerization reaction of ethylenediaminetetraacetic dianhydride（EDTAD） and piperazine（PA） to give poly（ethylenediaminetetraacetic dianhydride-copiperazine） （PEP）.The obtained polymers＇ structure was characterized by FTIR and ^（13）C NMR.The backbone of the polymer linked by amide bond and abundant of carboxyl groups as pendant group could form strong intermolecular and intramolecular hydrogen bond at lower temperature and dissociate at higher temperature,resulting in the polymer with thermo-sensitivity.The aqueous solution of PEP at lower temperature（〈20℃） showed micro-gel formation and transformed to transparent solution at higher temperature（〉40℃）.Transition temperature shifted to higher value with the increasing of concentration.The hydrogel exhibited reversible phase transition and the transmittance change was not weakened by multiple temperature changes.