Nucleocapsid Protein Subunits of Simian Virus 5, Newcastle Disease Virus, and Sendai Virus

Helical nucleocapsids of each of the paramyxoviruses simian virus 5 (SV5), Newcastle disease virus (NDV), and Sendai virus have been isolated in two different forms. One form contains larger protein subunits and is obtained from mature virions or infected cells dispersed by ethylenediaminetetraacetic acid. The other form possesses smaller subunits and is obtained from infected cells dispersed by trypsin. The estimated molecular weights of the larger subunits in the three viruses are similar: SV5, 61,000; Sendai virus, 60,000; NDV, 56,000. The smaller nucleocapsid subunits are also very similar: SV5, 43,000; Sendai virus, 46,000; NDV, 47,000. The helical nucleocapsid composed of the smaller subunit appears to be less flexible and more stable than that formed by the larger subunit. There is suggestive evidence that conversion of the larger subunit to the smaller by proteolytic cleavage may occur intracellularly. The possibility that such a mechanism could be involved in the accumulation of nucleocapsid in cells persistently infected with paramyxoviruses is discussed.     

Innovative Toolbox for the Quantification of Drosophila C Virus,Drosophila A Virus,and Nora Virus

Quantification of viral replication underlies investigations into host-virus interactions. In Drosophila melanogaster, persistent infections with Drosophila C virus, Drosophila A virus, and Nora virus are commonly observed in nature and in laboratory fly stocks. However, traditional endpoint dilution assays to quantify infectious titers are not compatible with persistently infecting isolates of these viruses that do not cause cytopathic effects in cell culture. Here we present a novel assay based on immunological detection of Drosophila C virus infection that allows quantification of infectious titers for a wider range of Drosophila C virus isolates. We also describe strand specific RT-qPCR assays for quantification of viral negative strand RNA produced during Drosophila C virus, Drosophila A virus, and Nora virus infection. Finally, we demonstrate the utility of these assays for quantification of viral replication during oral infections and persistent infections with each virus.     

利用寡核苷酸微阵列技术对HBV、HCV、HIV、HAV、GBV-C/HGV和B19进行同时监测的初步研究

探讨研制能同时检测HBV、HCV、HIV、HAV、GBV-C/HGV和B19的微阵列监控芯片。根据病毒公开发表序列,序列比对,得出保守区域,设计病毒的特异性检测探针,同时设置阴性、阳性参照探针,制备监控微阵列。利用随机引物PCR方法标记样品中的病毒靶序列,标记产物与微阵列上的探针杂交,清洗、扫描后进行结果分析。通过对质粒或模式分子的检测以及经HBV、HCV、HIV临床标本的验证,发现该微阵列监控芯片具有良好的特异性。其对质粒的检测灵敏度可达102病毒拷贝数,对临床标本的检测灵敏度可达103病毒拷贝数。此外,该微阵列监控芯片可检测出病毒混合感染血清。为微阵列监控芯片应用于此六种血液病毒的检测打下一定的基础。     

Polynucleotide Ligase Activity in Cells Infected with Simian Virus 40, Polyoma Virus, or Vaccinia Virus

The conversion of simian virus 40 (SV40) component II deoxyribonucleic acid to component I has been used to assay polynucleotide ligase in extracts of tissue culture cells. All cell types examined, including chicken, hamster, mouse, monkey, and human cells, contained adenosine triphosphate-dependent ligase. After infection of mouse embryo, monkey kidney, and HeLa cells with polyoma virus, SV40, and vaccinia virus, respectively, the enzyme activity increased, but its cofactor requirement was unchanged. In vaccinia virus-infected cells, the increased activity was localized in the cytoplasm. Ligase induction occurred in the presence of cytosine arabinoside but was prevented by puromycin. Rifampicin blocked the production of infectious vaccinia particles but had little effect on the induction of ligase.     

Microtiter Tests for Detecting Antibody in Bovine Serum to Parainfluenza 3 Virus, Infectious Bovine Rhinotracheitis Virus, and Bovine Virus Diarrhea Virus

Microneutralization tests for detection of antibody in bovine serum to three bovine viruses are described. The Madin-Darby bovine kidney cell line was used with parainfluenza 3 virus (PI 3), whereas serially cultivated bovine embryonic kidney cells were used for infectious bovine rhinotracheitis virus and bovine virus diarrhea virus. Comparison of micro-hemagglutination-inhibition (HI) with micro-serum-neutralization (SN) tests for PI 3 showed the SN test to be more sensitive, more specific, and therefore more useful than the HI test for detecting antibody. Although the effect of trypsin-periodate treatment of serum was to reduce the HI titer of numerous sera by a twofold dilution, sufficient evidence could not be found to indicate that nonspecific HI inhibitors to PI 3 are present in bovine sera.     

Cucumis sativus Cryptic Virus, a New Virus in Cucumber

Isometric virus-like particles (VLPs) have been purified from cucumber leaf tissue. Three dsRNA segments with estimated molecular weights of 1.8, 1.1 and 1.0 × 10⁶d have been isolated from VLPs occurring in CsCl density gradient fractions but were also readily detected in preparations from as little as 1 g of fresh leaf tissue. The VLPs resemble dsRNA containing cryptic viruses and have been named Cucumis sativus cryptic virus (CsCV).     

Long-Term Shedding of Influenza Virus,Parainfluenza Virus,Respiratory Syncytial Virus and Nosocomial Epidemiology in Patients with Hematological Disorders

Respiratory viruses are a cause of upper respiratory tract infections (URTI), but can be associated with severe lower respiratory tract infections (LRTI) in immunocompromised patients. The objective of this study was to investigate the genetic variability of influenza virus, parainfluenza virus and respiratory syncytial virus (RSV) and the duration of viral shedding in hematological patients. Nasopharyngeal swabs from hematological patients were screened for influenza, parainfluenza and RSV on admission as well as on development of respiratory symptoms. Consecutive swabs were collected until viral clearance. Out of 672 tested patients, a total of 111 patients (17%) were infected with one of the investigated viral agents: 40 with influenza, 13 with parainfluenza and 64 with RSV; six patients had influenza/RSV or parainfluenza/RSV co-infections. The majority of infected patients (n = 75/111) underwent stem cell transplantation (42 autologous, 48 allogeneic, 15 autologous and allogeneic). LRTI was observed in 48 patients, of whom 15 patients developed severe LRTI, and 13 patients with respiratory tract infection died. Phylogenetic analysis revealed a variety of influenza A(H1N1)pdm09, A(H3N2), influenza B, parainfluenza 3 and RSV A, B viruses. RSV A was detected in 54 patients, RSV B in ten patients. The newly emerging RSV A genotype ON1 predominated in the study cohort and was found in 48 (75%) of 64 RSV-infected patients. Furthermore, two distinct clusters were detected for RSV A genotype ON1, identical RSV G gene sequences in these patients are consistent with nosocomial transmission. Long-term viral shedding for more than 30 days was significantly associated with prior allogeneic transplantation (p = 0.01) and was most pronounced in patients with RSV infection (n = 16) with a median duration of viral shedding for 80 days (range 35–334 days). Long-term shedding of respiratory viruses might be a catalyzer of nosocomial transmission and must be considered for efficient infection control in immunocompromised patients.     

Proteins and Glycoproteins of Paramyxoviruses: a Comparison of Simian Virus 5, Newcastle Disease Virus, and Sendai Virus

The polypeptides of three paramyxoviruses (simian virus 5, Newcastle disease virus, and Sendai virus) were separated by polyacrylamide gel electrophoresis. Glycoproteins were identified by the use of radioactive glucosamine as a carbohydrate precursor. The protein patterns reveal similarities among the three viruses. Each virus contains at least five or six proteins, two of which are glycoproteins. Four of the proteins found in each virus share common features with corresponding proteins in the other two viruses, including similar molecular weights. These four proteins are the nucleocapsid protein (molecular weight 56,000 to 61,000), a larger glycoprotein (molecular weight 65,000 to 74,000), a smaller glycoprotein (molecular weight 53,000 to 56,000), and a major protein which is the smallest protein in each virion (molecular weight 38,000 to 41,000).     

Common Themes of Antibody Maturation to Simian Immunodeficiency Virus, Simian-Human Immunodeficiency Virus, and Human Immunodeficiency Virus Type 1 Infections

Characterization of virus-specific immune responses to human immunodeficiency virus type 1 (HIV-1) and simian immunodeficiency virus (SIV) is important to understanding the early virus-host interactions that may determine the course of virus infection and disease. Using a comprehensive panel of serological assays, we have previously demonstrated a complex and lengthy maturation of virus-specific antibody responses elicited by attenuated strains of SIV that was closely associated with the development of protective immunity. In the present study, we expand these analyses to address several questions regarding the nature of the virus-specific antibody responses to pathogenic SIV, SIV/HIV-1 (SHIV), and HIV-1 infections. The results demonstrate for the first time a common theme of antibody maturation to SIV, SHIV, and HIV-1 infections that is characterized by ongoing changes in antibody titer, conformational dependence, and antibody avidity during the first 6 to 10 months following virus infection. We demonstrate that this gradual evolution of virus-specific antibody responses is independent of the levels of virus replication and the pathogenicity of the infection viral strain. While the serological assays used in these studies were useful in discriminating between protective and nonprotective antibody responses during evaluation of vaccine efficacy with attenuated SIV, these same assays do not distinguish the clinical outcome of infection in pathogenic SIV, SHIV, or HIV-1 infections. These results likely reflect differences in the immune mechanisms involved in mediating protection from virus challenge compared to those that control an established viral infection, and they suggest that additional characteristics of both humoral and cellular responses evolve during this early immune maturation.     

Malsoor Virus,a Novel Bat Phlebovirus,Is Closely Related to Severe Fever with Thrombocytopenia Syndrome Virus and Heartland Virus

During a survey in the year 2010, a novel phlebovirus was isolated from the Rousettus leschenaultii species of bats in western India. The virus was identified by electron microscopy from infected Vero E6 cells. Phylogenic analysis of the complete genome showed its close relation to severe fever with thrombocytopenia syndrome (SFTS) and Heartland viruses, which makes it imperative to further study its natural ecology and potential as a novel emerging zoonotic virus.     

Seroprevalence of Human Immunodeficiency Virus,Hepatitis B Virus,Hepatitis C Virus,and Treponema pallidum Infections among Blood Donors on Bioko Island,Equatorial Guinea

Background

Regular screening of transfusion-transmissible infections (TTIs), such as human immunodeficiency virus (HIV), hepatitis B and hepatitis C virus (HBV and HCV, respectively), and Treponema pallidum, in blood donors is essential to guaranteeing clinical transfusion safety. This study aimed to determine the seroprevalence of four TTIs among blood donors on Bioko Island, Equatorial Guinea (EG).

Methods

A retrospective survey of blood donors from January 2011 to April 2013 was conducted to assess the presence of HIV, HBV, HCV and T. pallidum. The medical records were analyzed to verify the seroprevalence of these TTIs among blood donations stratified by gender, age and geographical region.

Results

Of the total 2937 consecutive blood donors, 1098 (37.39%) had a minimum of one TTI and 185 (6.29%) harbored co-infections. The general seroprevalence of HIV, HBV, HCV and T. pallidum were 7.83%, 10.01%, 3.71% and 21.51%, respectively. The most frequent TTI co-infections were HBV-T. pallidum 60 (2.04%) and HIV-T. pallidum 46 (1.57%). The seroprevalence of HIV, HBV, HCV and T. pallidum were highest among blood donors 38 to 47 years, 18 to 27 years and ≥ 48 years age, respectively (P<0.05). The seroprevalence of TTIs varied according to the population from which the blood was collected on Bioko Island.

Conclusions

Our results firstly provide a comprehensive overview of TTIs among blood donors on Bioko Island. Strict screening of blood donors and improved hematological examinations using standard operating procedures are recommended.     

应用免疫电镜技术快速检测菜豆黄花叶病毒、马铃薯M病毒和燕麦花叶病毒

应用免疫吸附电流技术(ISEM)可有效地检测腐汁液中的菜豆黄花叶病毒(BYMV)、马铃薯M病毒(PVM)和燕麦花叶病毒(OMV)。BYMV,PVM和OMV三种抗血清的适宜工作浓度和对铜网的适宜包被时间均为1000倍和1小时,对同源病毒的适宜捕获时间分别为4℃下2、2和8小时。PVM和OMV的病汁液检测灵敏度均为稀释4000倍,而BYMV病汁液稀释16000倍时还能检测到少量病毒料子。ISEM捕获法和修饰法的结果表明,这三种病毒之间无血清学交叉反应。     

Virus assembly, allostery and antivirals

Assembly of virus capsids and surface proteins must be regulated to ensure that the resulting complex is an infectious virion. In this review, we examine assembly of virus capsids, focusing on hepatitis B virus and bacteriophage MS2, and formation of glycoproteins in the alphaviruses. These systems are structurally and biochemically well-characterized and are simplest-case paradigms of self-assembly. Published data suggest that capsid and glycoprotein assembly is subject to allosteric regulation, that is regulation at the level of conformational change. The hypothesis that allostery is a common theme in viruses suggests that deregulation of capsid and glycoprotein assembly by small molecule effectors will be an attractive antiviral strategy, as has been demonstrated with hepatitis B virus.     

Virus Entry, Assembly, Budding, and Membrane Rafts

As intracellular parasites, viruses rely heavily on the use of numerous cellular machineries for completion of their replication cycle. The recent discovery of the heterogeneous distribution of the various lipids within cell membranes has led to the proposal that sphingolipids and cholesterol tend to segregate in microdomains called membrane rafts. The involvement of membrane rafts in biosynthetic traffic, signal transduction, and endocytosis has suggested that viruses may also take advantage of rafts for completion of some steps of their replication cycle, such as entry into their cell host, assembly, and budding. In this review, we have attempted to delineate all the reliable data sustaining this hypothesis and to build some models of how rafts are used as platforms for assembly of some viruses. Indeed, if in many cases a formal proof of raft involvement in a virus replication cycle is still lacking, one can reasonably suggest that, owing to their ability to specifically attract some proteins, lipid microdomains provide a particular milieu suitable for increasing the efficiency of many protein-protein interactions which are crucial for virus infection and growth.