The Perturbed Riemann Problem for a Geometrical Optics System

The perturbed Riemann problem for a hyperbolic system of conservation laws arising in geometrical optics with three constant initial states is solved.By studying the interactions among of the delta-shock,vacuum,and contact discontinuity,fourteen kinds of structures of Riemann solutions are obtained.The compound wave solutions consisting of delta-shocks,vacuums,and contact discontinuities are found.The single and double closed vacuum cavitations develop in solutions.Furthermore,it is shown that the solutions of the Riemann problem for the geometrical optics system are stable under certain perturbation of the initial data.Finally,the numerical results completely coinciding with theoretical analysis are presented.

2020年猪病流行情况与2021年流行趋势及防控对策

文章着重概述了2020年我国非洲猪瘟的流行和发生情况,提及了猪繁殖与呼吸综合征、猪瘟、猪伪狂犬病、猪流行性腹泻等重要猪病。分析了2021年非洲猪瘟的流行趋势,并提出了相应的防控策略。

2019年猪病流行情况与2020年流行趋势及防控对策

文章结合实验室的监测数据,概述了2019年我国非洲猪瘟、猪繁殖与呼吸综合征、猪瘟、猪伪狂犬病、猪流行性腹泻等重要猪病的流行状况,着重总结了非洲猪瘟疫情发生情况。分析了2020年非洲猪瘟等疫病的流行趋势,同时提出了坚持生物安全、严格处置非洲猪瘟疫情等防控策略。

艾曲波帕对难治性原发免疫性血小板减少症的疗效及其对细胞免疫功能的影响

探讨艾曲波帕在难治性原发免疫性血小板减少症(ITP)治疗中的临床效果及其对细胞免疫功能的影响。选取2019年1月至2022年10月我院收治的132例难治性ITP患者纳入研究,将其分为联合治疗组(44例)、单一治疗组(44例)和对照组(44例),联合治疗组给予艾曲波帕联合长春地辛治疗,单一治疗组给予艾曲波帕单药治疗,对照组仅给予生活方式干预治疗,疗程均为12周。比较三组临床疗效及不良反应,检测治疗前后三组血小板计数(PLT)、出血时间(BT)、T淋巴细胞亚群(CD_(4)^(+)、CD_(8)^(+))、B淋巴细胞亚群(CD_(19)^(+)、CD_(20)^(+))、Th1细胞因子(IFN-γ、IL-2)及Th2细胞因子(IL-5、IL-4)水平变化。治疗后,单一治疗组完全反应率明显高于对照组,联合治疗组完全反应率明显高于单一治疗组(均P<0.05)。单一治疗组治疗总有效率高于对照组(P<0.05);联合治疗组总有效率高于单一治疗组(P<0.05)。与对照组比较,单一治疗组治疗后PLT及BT检测值均明显改善(P<0.05);与单一对照组比较,联合治疗组治疗后PLT及BT检测值均明显改善(P<0.05)。与对照组比较,单一治疗组治疗后CD_(4)^(+)/CD_(8)^(+)及CD_(19)^(+)/CD_(20)^(+)均明显改善(P<0.05);与单一治疗组比较,联合治疗组治疗后CD_(4)^(+)/CD_(8)^(+)及CD_(19)^(+)/CD_(20)^(+)均明显改善(P﹤0.05);与对照组比较,单一治疗组及联合治疗组治疗12周后血清IFN-γ、IL-2水平明显较低,而血清IL-5、IL-4水平明显较高(P<0.05);与单一治疗组比较,联合治疗组治疗12周后血清IFN-γ、IL-2水平明显较低,而血清IL-5、IL-4水平明显较高(P<0.05);三组不良反应发生率比较无显著差异(P>0.05)。对于难治性原发免疫性血小板减少症患者,艾曲波帕与免疫抑制剂联合治疗安全有效,利于细胞免疫功能恢复。

Identification of Nonstructural Protein 8 as the N-Terminus of the RNA-Dependent RNA Polymerase of Porcine Reproductive and Respiratory Syndrome Virus

Porcine reproductive and respiratory syndrome virus (PRRSV) is a member within the family Arteriviridae of the order Nidovirales. Replication of this positive-stranded RNA virus within the host cell involves expression of viral replicase proteins encoded by two ORFs, namely ORF1 a and ORF1 b. In particular, translation of ORF1 b depends on a-1-ribosomal frameshift strategy. Thus, nonstructural protein 9 (nsp9), the first protein within ORF1 b that specifies the function of the viral RNA-dependent RNA polymerase, is expressed as the C-terminal extension of nsp8, a small nsp that is encoded by ORF1 a. However, it has remained unclear whether the mature form of nsp9 in virus-infected cells still retains nsp8,addressing which is clearly critical to understand the biological function of nsp9. By taking advantage of specific antibodies to both nsp8 and nsp9, we report the following findings. (1) In infected cells, PRRSV nsp9 was identified as a major product with a size between 72 and 95 k Da (72–95 KDa form), which exhibited the similar mobility on the gel to the in vitro expressed nsp8–9 ORF1 b, but not the ORF1 b-coded portion (nsp9 ORF1 b). (2) The antibodies to nsp8, but not to nsp7 or nsp10, could detect a major product that had the similar mobility to the 72–95 KDa form of nsp9. Moreover, nsp9 could be co-immunoprecipitated by antibodies to nsp8, and vice versa. (3) Neither nsp4 nor nsp2 PLP2 was able to cleave nsp8–nsp9 in vitro. Together, our studies provide experimental evidence to suggest that nsp8 is an N-terminal extension of nsp9.Our findings here paves way for further charactering the biological function of PRRSV nsp9.

Nsp2 and GP5-M of Porcine Reproductive and Respiratory Syndrome Virus Contribute to Targets for Neutralizing Antibodies

Porcine reproductive and respiratory syndrome virus(PRRSV)is characterized by its genetic variation and limited cross protection among heterologous strains.Even though several viral structural proteins have been regarded as inducers of neutralizing antibodies(NAs)against PRRSV,the mechanism underlying limited cross-neutralization among heterologous strains is still controversial.In the present study,examinations of NA cross reaction between a highly pathogenic PRRSV(HP-PRRSV)strain,JXwn06,and a low pathogenic PRRSV(LP-PRRSV)strain,HB-1/3.9,were conducted with viral neutralization assays in MARC-145 cells.None of the JXwn06-hyperimmuned pigs’sera could neutralize HB-1/3.9 in vitro and vice versa.To address the genetic variation between these two viruses that are associated with limited crossneutralization,chimeric viruses with coding regions swapped between these two strains were constructed.Viral neutralization assays indicated that variations in nonstructural protein 2(nsp2)and structural proteins together contribute to weak cross-neutralization activity between JXwn06 and HB-1/3.9.Furthermore,we substituted the nsp2-,glycoprotein2(GP2)-,GP3-,and GP4-coding regions together,or nsp2-,GP5-,and membrane(M)protein-coding regions simultaneously between these two viruses to construct chimeric viruses to test cross-neutralization reactivity with hyperimmunized sera induced by their parental viruses.The results indicated that the swapped nsp2 and GP5-M viruses increased the neutralization reactivity with the donor strain antisera in MARC-145 cells.Taken together,these results show that variations in nsp2 and GP5-M correlate with the limited neutralization reactivity between the heterologous strains HP-PRRSV JXwn06 and LP-PRRSV HB-1/3.9.

Biharmonic Maps from Tori into a 2-Sphere

Biharmonic maps are generalizations of harmonic maps. A well-known result on harmonic maps between surfaces shows that there exists no harmonic map from a torus into a sphere(whatever the metrics chosen) in the homotopy class of maps of Brower degree±1. It would be interesting to know if there exists any biharmonic map in that homotopy class of maps. The authors obtain some classifications on biharmonic maps from a torus into a sphere, where the torus is provided with a flat or a class of non-flat metrics whilst the sphere is provided with the standard metric. The results in this paper show that there exists no proper biharmonic maps of degree±1 in a large family of maps from a torus into a sphere.

A novel strategy to attenuate porcine reproductive and respiratory syndrome virus by inhibiting viral replication in the target pulmonary alveolar macrophages via hematopoietic-specific miR-142

Porcine reproductive and respiratory syndrome virus(PRRSV)is an economically important pathogen for the global pork industry.Although modified live virus(MLV)vaccines are commonly used for PRRSV prevention and control,they still carry a risk of infecting the host and replicating in target cells,thereby increasing the likehood of virus recombination and reversion to virulence.In this study,we inserted the target sequence of miR-142 into the nsp2 hypervariable region of PRRSV to inhibit viral replication in its host cells of pigs,with the aim of achieving virus attenuation.The chimeric virus RvJX-miR-142t was successfully rescued and retained its growth characteristics in MARC-145 cells.Furthermore,it did not replicate in MARC-145 cells transfected with miRNA-142 mimic.We also observed limited replication ability of RvJX-miR-142t in pulmonary alveolar macrophages,which are the main cell types that PRRSV infects.Our animal inoculation study showed that pigs infected with RvJX-miR-142t displayed less severe clinical symptoms,lower viremia titers,lighter lung lesions,and significantly lower mortality rates during the first 7 days post-inoculation,in comparison to pigs infected with the backbone virus RvJXwn.We detected a partially deletion of the miR-142 target sequence in the RvJX-miR-142t genome at 14 dpi.It is highly possible that the reversion of viral virulence observed in the later timepoints of our animal experiment was caused by that.Our study provided a new strategy for attenuating PRRSV and confirmed its effectiveness.However,further studies are necessary to increase the stability of this virus under host selection pressure.

The replicase protein nsp2 of Chinese highly pathogenic porcine reproductive and respiratory virus is involved in protective immunity by promoting viral clearance

The genome segment for replicase protein nsp2 represents the fastest evolving region of porcine reproductive and respiratory syndrome virus(PRRSV),and our previous studies have shown that the PRRSV nsp2 genetic variation contributes to poor cross-neutralization.By using in vitro antibody absorption assay,here we show that the papainlike protease 2(PLP2)domain of nsp2 is a target of neutralizing antibodies.This was further verified by cross-neutralization assay with a series of inter-lineage chimeric mutants between the Chinese highly pathogenic PRRSV(HP-PRRSV)strain JXwn06 and the low virulent NADC30-like strain CHsx1401(lineage 1).The role of nsp2 in protective immunity was subsequently tested in a one-month SPF piglet model by immunizing the piglets with CHsx1401 or its derivatives carrying JXwn06 structural protein region(SP)alone(CHsx1401-SPJX)or in combination with PLP2 region(CHsx1401-SPplp2JX),or the whole nsp2 region(CHsx1401-SPnsp2JX),followed by challenge with JXwn06 at 42 days post immunization,a time point when the viremia was undetectable.All chimera groups were protected from the challenge by JXwn06,whereas the group CHsx1401 failed to provide beneficial protection.Interestingly,the group CHsx1401-SPnsp2JX,but not CHsx1401-SPplp2JX,showed the lowest lung microscopic lesions and viral tissue load.Significantly,the vaccine virus CHsx1401-SPnsp2JX was undetectable in the examined tissues,and so was for the challenge virus except for one piglet,highlighting an important role of HP-PRRSV nsp2 in promoting viral clearance.The findings provide insight into the mechanisms underlying the protective immunity against PRRSV and have important implications in PRRSV vaccine development.