Assembly and Maturation of a T = 4 Quasi-Equivalent Virus Is Guided by Electrostatic and Mechanical Forces

Nudaurelia capensis ω virus (NωV) is a eukaryotic RNA virus that is well suited for the study of virus maturation. The virus initially assembles at pH 7.6 into a marginally stable 480-Å procapsid formed by 240 copies of a single type of protein subunit. During maturation, which occurs during apoptosis at pH 5.0, electrostatic forces guide subunit trajectories into a robust 410-Å virion that is buttressed by subunit associated molecular switches. We discuss the competing factors in the virus capsid of requiring near-reversible interactions during initial assembly to avoid kinetic traps, while requiring robust stability to survive in the extra-cellular environment. In addition, viruses have a variety of mechanisms to deliver the genome, which must remain off while still inside the infected cell, yet turn on under the proper conditions of infection. We conclude that maturation is the process that provides a solution to these conflicting requirements through a program that is encoded in the procapsid and that leads to stability and infectivity.     

Surveillance of Bungowannah Pestivirus in the Upper Midwestern USA

Pestiviruses, a genetically and antigenically highly diverse group, include one of the most historically significant swine pathogens, that is, classical swine fever virus. In Australia, investigations into swine outbreaks characterized by neonatal mortality, stillbirths and mummified foetuses resulted in the discovery of a new pestivirus, Bungowannah virus. This finding raised the possibility that Bungowannah virus, or a variant thereof, was circulating in swine herds elsewhere in the World. If so, it raised the possibility of a pestivirus emerging as a new swine disease with unknown consequences for animal health and food safety. Thus, we developed three specific qRT‐PCR assays to evaluate tissue samples from undiagnosed cases of abortion or respiratory disease for evidence of Bungowannah virus. Examination of 64 samples collected between the Fall of 2007 and Spring of 2010 tested negative for all three genes examined. We conclude that Bungowannah‐like pestivirus is unlikely to be present in swine in the upper Midwestern USA.     

The genetic variability of glycoproteins among respiratory syncytial virus subtype A in China between 2009 and 2013

Human respiratory syncytial virus (RSV) is the leading cause of acute lower respiratory tract infections in infants and children under 5 years of age. The novel genotype ON1 has a 72-nucleotide duplication, which is the largest duplicated genome portion of RSV. Whether the ON1 genotype will follow the pattern of the BA genotype, which has a 60-nucleotide duplication, and become the predominant RSV-A strain is a global concern. To obtain information regarding the prevalence of the ON1 genotype in Chongqing in Southwestern China, we examined the circulation pattern of RSV-A identified over four consecutive years (June 2009 to August 2013). In this study, 312 (12%) RSV-A strains were isolated from 2601 nasopharyngeal aspirates, and partial G gene was sequenced successfully in 250 isolates. Of the sequenced Chongqing RSV-A isolates, 237 (94.8%) strains were the NA1 genotype, 4 (1.6%) strains were the NA3 genotype, 4 (1.6%) strains were the NA4 genotype, 1 (0.4%) strain was the GA1 genotype, and 4 (1.6%) strains were identified as the ON1 genotype. Analysis of the distribution, phylogeny, and evolution of the ON1 strains that were collected globally until December 2013 revealed that the ON1 genotype has rapidly disseminated across the world under positive selection pressures. Future studies will determine whether this new genotype will continue to spread and become the dominant strain of RSV-A worldwide. These findings may contribute to the understanding of RSV evolution and to the potential development of a vaccine against RSV.     

Dengue Virus Type 3, South Pacific Islands, 2013

After an 18-year absence, dengue virus serotype 3 reemerged in the South Pacific Islands in 2013. Outbreaks in western (Solomon Islands) and eastern (French Polynesia) regions were caused by different genotypes. This finding suggested that immunity against dengue virus serotype, rather than virus genotype, was the principal determinant of reemergence.     

Consultation on dengue vaccines: Progress in understanding protection, 26–28 June 2013, Rockville,Maryland

There is an unmet need for a dengue vaccine to further prevent the spread of this disease and contain the growing pandemic. To this end several vaccine companies and academic groups are actively pursuing the development of a tetravalent vaccine to prevent dengue. In the last few years progress has been made in this area, including the first results of a vaccine efficacy trial and improved understanding of the immune responses to the infection. Despite this progress, development of dengue vaccines faces important challenges including the need for a vaccine that induces balanced immune responses against all dengue strains and an incomplete understanding of the mechanism(s) of protection against infection and disease. This is a summary of a Consultation on dengue vaccines held in June 26–28, 2013 by the National Institute of Allergy and Infectious Diseases (part of the US National Institutes of Health) and the Dengue Vaccine Initiative (part of the International Vaccine Institute). The primary goal of this consultation was to review the progress in dengue vaccine development, evaluate the known mechanism of protection of dengue vaccines and discuss avenues for future research.     

Assessment of an immunomarking technique for the study of dispersal of Culicoides biting midges

Capture–mark–recapture techniques are used to determine the dispersal and survival of arthropods, including vector groups such as Culicoides. An assumption of these studies is that capture and the subsequent marking process does not impact of the survival and behaviour of the marked individual. The small size of Culicoides means that a significant mortality and disruption of normal behaviour such as host-location can be caused by the process of collection. Here we evaluate a technique, novel to the study of dispersal in vectors, to mark Culicoides directly and indirectly without prior capture. The acquisition and subsequent detection of marker protein by Culicoides exposed to a treated substrate was investigated in the laboratory. The technique was then assessed in a small-scale field trial where a defined section of resting habitat was sprayed with an egg white solution and Culicoides caught within the vicinity were tested for the presence of egg protein. It was found that up to 100% of Culicoides acquired the protein marker in the laboratory with no apparent impact on survival. In the field, pools of Culicoides obsoletus collected next to the treated area were found to be positive for the protein, suggesting that the technique could be used in larger-scale studies. The definition of a behaviourally non-invasive technique for marking Culicoides will greatly increase our understanding of the natural dispersal behaviour of Culicoides and other vectors.     

河南省新报告HIV感染者中丙型肝炎病毒感染状况及其影响因素分析

目的 了解河南省新报告HIV感染者中丙型肝炎病毒（HCV）感染情况及其相关影响因素。方法 对2012年7月1日至2013年6月30日河南省所有新确证上报的HIV-1感染者进行信息整理、HIV-1 BED新发感染检测和HCV抗体检测。结果 河南省该期间新确证上报2 049例HIV-1感染者中HCV抗体阳性率为14.87%（271/1 887），BED阳性比例（新发感染比例）为26.34%（497/1 887）。新发HIV-1感染者中HCV抗体阳性率较既往HIV-1感染者低，20～39岁组HIV-1感染者的HCV抗体阳性率较其他年龄组低，个别地区HIV-1感染者的HCV抗体阳性率较高，经注射吸毒感染HIV-1者中HCV抗体阳性率较高。结论 新发感染、年龄、传播途径和地区分布是河南省新报告HIV-1感染者中HCV感染率的影响因素，应有针对性地开展此人群的丙型肝炎防治工作。