Characteristics of hemagglutinin-neuraminidase gene of human parainfluenza virus type 3 among patients with acute respiratory tract infection in Henan Province / 中华微生物学和免疫学杂志

Objective:To analyze the molecular characteristics of hemagglutinin-neuraminidase (HN) gene of human parainfluenza virus type 3 (HPIV3) among the cases with acute respiratory tract infection (ARI) in Henan Province.Methods:Nasal/throat swab samples collected from patients with severe acute respiratory tract infection (SARI) in Luohe and patients with influenza-like illness (ILI) in Zhengzhou were used in this study. HPIV nucleic acids in the samples were detected using real-time fluorescent PCR. HPIV3-positive samples were subjected to RT-PCR for the amplification of HN genes and the sequences were analyzed with Sanger method. CExpress and MEGA7.0 software were used for sequences editing, evolution tree construction and gene sequence analysis.Results:A total of 374 throat swab samples collected form ARI cases in Luohe and Zhengzhou were tested and 20 (5.3%) of them were positive for HPIV3. Eighteen HPIV3 HN gene sequences were successfully amplified and all belonged to C3 subgroups, including 16 sequences of C3f genotype and two sequences of C3a genotype. The 18 HN gene sequences shared the homology of 97.6%-100.0% in nucleotide and 99.3%-100.0% in amino acid, but the differences between them and the prototype strain Wash/47885/57 were significant. There were 12 amino acid mutations shared by them, including four function-related mutations (H295Y, I391V, D556N and I53T). There were no significant differences in the nucleotide or amino acid sequences as compared with the epidemic strain of China/BCH4210A/2014.Conclusions:The C3f and C3a branches of HPIV3 were the epidemic genotypes in Henan Province in recent years and a local circulating prevalence might be established. Continuous and in-depth monitoring of HPIV3 C3 subtype would be of great significance for the prevention and control of HPIV3-associated diseases.

Analysis of gene mutation in the interaction domain of head and stalk of Newcastle disease virus hemagglutinin-neuraminidase glycoprotein / 中华实验和临床病毒学杂志

Objective@#To identify the function of 91-112 amino acids (aa) fragment, the interaction domain of head and stalk of Newcastle disease virus(NDV) HN glycoprotein, and clarify the role of the fragment in promoting cell specific membrane fusion.@*Methods@#The specific gene sequences were identified by aligning 91-112 amino acids of NDV HN protein with amino acids of MeV H, RSV G, hPIV3 HN protein. The fragment deletion, fragment substitution and intermolecular homologous recombination method were combined to construct the deletion mutant, De(HN), and three chimeras, Ch(MeV), Ch(RSV), Ch(hPIV3). Cationic transfection reagent was used to transfect the plasmids into baby hamster kidney cells (BHK-21), in which vaccinia virus-T7 RNA polymerase expression system was expressed. Indirect immunofluorescence assay (IIFA) and flow cytometry (FCM) were executed to analyze the cell surface expression level. Cell fusion promotion activity, receptor recognition activity and neuraminidase activity of each mutant were also detected.@*Results@#Cell surface expression efficiency of De(HN) and Ch(MeV), Ch(RSV), Ch(hPIV3) proteins were 9.04%, 82.20%, 70.16%, 75.65% of that of wild-type (wt) HN. Fusion promotion activity of De(HN), Ch(MeV), Ch(RSV), Ch(hPIV3) were 3.83%, 24.76%, 29.42%, 57.84% of that of wt HN. The fusion promotion activity of De(HN) almost disappeared and syncytium couldn’t be found under the microscope. Hemadsorption activity was 13.48%, 36.25%, 34.93%, 65.22%, respectively (P<0.05), which was consistent with the fusion promotion activity of mutant proteins. Neuraminidase activity was 10.81%, 54.42%, 50.13%, 60.35% of that of wt HN, respectively (P<0.05).@*Conclusions@#The amino acids fragment (91-112) of NDV HN protein plays an important role in promotion fusion. The loss of fusion promotion activity of De(HN) protein was related to the failure of effective cell surface expression of the mutant.

Biological Property of Recombinant Hemagglutinin-Neuraminidase Protein of Avian Paramyxovirus Type 6 Expressed by Recombinant Baculovirus

Hemagglutination inhibition (HI) test employing whole virus antigen is a prescribed serological test for serotyping, diagnosis and surveillance for avian paramyxoviruses (APMVs). For use as alternative to the virus antigen, hemagglutinin-neuraminidase (HN) protein gene of the wild duck isolate APMV-6/WB12-163FS of APMV serotype 6 (APMV-6) was amplified, cloned and expressed in Spodoptera frugiperda insect cells. The HN gene of 1,842 bps in length showed nucleotide and amino acid homology of 93.4% and 97.1%, respectively with that of APMV-6 prototype strain. Putative sialic acid binding motif and potential N-linked glycosylation sites were conserved. In Western blot analysis, the expressed protein had a molecular mass of 66 kDa and reacted specifically with antiserum to APMV-6. In addition, the recombinant HN protein showed biological properties such as hemagglutination (HA) and elution. The recombinant HN protein produced from infected cells showed high HA titers (approximately 2(13) HA unit/ml). The HA activity of the recombinant HN protein was inhibited by antisera to APMV-6. In cross HA inhibition test, the recombinant HN protein had the highest titers with antisera to homologous APMV serotype, although there was weak cross reaction with some of antisera to other APMV serotypes. Our results indicated that recombinant APMV-6 HN protein would have the potential as alternative to the APMV-6 antigen in HI assays.

Preparation and diagnostic utility of a hemagglutination inhibition test antigen derived from the baculovirus-expressed hemagglutinin-neuraminidase protein gene of Newcastle disease virus

A recombinant hemagglutinin-neuraminidase (rHN) protein from Newcastle disease virus (NDV) with hemagglutination (HA) activity was expressed in Spodoptera frugiperda cells using a baculovirus expression system. The rHN protein extracted from infected cells was used as an antigen in a hemagglutination inhibition (HI) test for the detection and titration of NDV-specific antibodies present in chicken sera. The rHN antigen produced high HA titers of 2(13) per 25 microL, which were similar to those of the NDV antigen produced using chicken eggs, and it remained stable without significant loss of the HA activity for at least 12 weeks at 4degrees C. The rHN-based HI assay specifically detected NDV antibodies, but not the sera of other avian pathogens, with a specificity and sensitivity of 100% and 98.0%, respectively, in known positive and negative chicken sera (n = 430). Compared with an NDV-based HI assay, the rHN-based HI assay had a relative sensitivity and specificity of 96.1% and 95.5%, respectively, when applied to field chicken sera. The HI titers of the rHN-based HI assay were highly correlated with those in an NDV-based HI assay (r = 0.927). Overall, these results indicate that rHN protein provides a useful alternative to NDV antigen in HI assays.

Mutational analysis of conserved amino acids in the fusion-promoting domain of Newcastle disease virus hemgglutinin-neuraminidase protein / 中华微生物学和免疫学杂志

Objective To determine the function of conserved amino acids in the fusion-promoting domain of Newcastle disease virus (NDV) hemagglutinin-neuraminidase (HN) protein,clearly understanding mechanism of cell fusion.MethodsUsing a PCR-based site-directed mutagenesis method and the method of homology recombination occurred in vivo to change six conservative amino acids into alanine respectively.Wild type (WT) and all mutant HN proteins were exepressed in BHK-21 cells by the vacciniaT7 RNA polymerase expression system.The amount of each HN protein at the cell surface was determined by fluorescence-activated cell sorter (FACS).Cell fusion efficiency,hemadsorption activity (or receptor binding activity) and neuraminidase activity were determined.Results There was no statistic difference of cell surface expression among WT and each mutant HN protein ( P＜0.05 ).Cell fusion efficiency of each mutant protein decreased to some extent,especially 1103A decreased to 14.2％ in head.Hemadsorption activity of mutant proteins were reduced in different extent,the maximum reduction of which was also 1103A,28.2％ of wt NDV HN.There was different neuraminidase activity among each mutant HN protein.L74A increased slightly to 118.6％.L110A decreased most to 5.2％.I103A decreased second most to 5.7％.Conclusion Conserved amino acids in fusion-promoting domain of NDV HN played an important role in cell fusion.I103 was identified as a key amino acid in this domain.

Caracterización biológica de tres aislamientos naturales del Rubulavirus porcino (México)

Biological characterization of three natural isolates of the porcine rubulavirus (Mexico). Porcine rubulavirus (PoRV) produces a neurological and reproductive syndrome in pigs called the blue-eye disease, known only from Mexico. Several isolates were grouped by the main symptoms presented during outbreaks: a) neurotropic in piglets, b) broadly neurotropic in piglets and gonadotropic in adults, and c) gonadotropic in adults. We studied some biological properties of three strains, which fall in one of each virus group: La Piedad Michoacán (LPM) and Producción Animal Cerdos 1 (PAC1) and 3 (PAC3), respectively. The analyzed viral properties are mainly related with the trans-membrane hemagglutinin-neuraminidase (HN) and fusion (F) proteins, such as cytopathic effect, hemolysis, hemagglutinating (HA) and neuraminidase (NA) activities. In the infection assays PAC1 strain presented the highest fusogenicity level; however, the most cytolytic strain was PAC3. In addition, HA and NA activities and viral genome of PAC3 strain was detected in supernatants during cell infection earlier than in the other two strains, which shows that PAC3 virions release from the host cell earlier than LPM and PAC1. Experimental determination in purified viruses shows that PAC3 presented a higher HA and NA activities; however, PAC1 shows other interesting properties, such as a high thermostability of HN and differences about substrate profile respect to LPM and PAC3. Our data suggest that NA activity is associated with the virulence of RVP. Rev. Biol. Trop. 56 (2): 487-499. Epub 2008 June 30.

El Rubulavirus porcino causa un síndrome neurológico y reproductivo en cerdos, hasta ahora reportado sólo en México. Los virus aislados se agrupan de acuerdo con los síntomas principales observados durante los brotes en: a) neutrópicos en lechones, b) neurotrópicos en lechones/gonadotrópicos en adultos y c) gonadotrópicos en adultos. En este trabajo se estudiaron tres cepas: La Piedad Michoacán (LPM) y Producción Animal "Cerdos" 1 (PAC1) y 3 (PAC3), ubicadas respectivamente en cada grupo. Las propiedades estudiadas se relacionan principalmente con dos proteínas de la envoltura viral, la hemaglutinina-neuraminidasa (HN) y la proteína de fusión (F). Se cuantificaron el efecto citopático y las actividades de hemólisis, hemaglutinación (HA) y neuraminidasa (NA). En cultivo celular la cepa PAC1 presentó una mayor actividad fusogénica, sin embargo PAC3 presentó la mayor actividad citolítica. La cepa PAC3 fue la primera en ser detectada en sobrenadante de células infectadas (HA, NA y genoma), lo que muestra que sus viriones son liberados al medio antes que las otras dos cepas. PAC3 tuvo las actividades más altas de HA y NA, sin embargo, PAC1 presentó una mayor termoestabilidad en estas actividades de HN y un perfil de substrato algo distinto de los observados para LPM y PAC3. Estos datos sugieren que la actividad de NA está relacionada con la virulencia del RVP.

Antigenicity and Hemaglutination Activity of a Recombinant Hemagglutinin-Neuraminidase of Paramyxovirus Tianjin Strain / 中国病毒学·英文版

Paramyxovirus Tianjin strain, a new genotype of Sendal virus, was isolated from the lungs of common cotton-eared marmoset that died of severe respiratory infection in the marmoset colonies. The 19.28% IgM positive rate in the young children with acute respiratory tract infection suggested a close relationship between Tianjin strain and humans. Hemagglutinin-neuraminidase (HN) is its major transmembrane glycoprotein responsible for viral attachment, penetration and release. To clear the relationship between HN structure and function of paramyxovirus Tianjin strain, rHN1, rHN2 and rHN3 overlapping the ectodomain of HN protein were expressed. Their antigenicity and hemaglutination activity, as well as cross reactivity to standard antisera against influenza virus type A, type B were analyzed. The results indicated expressed rHNs have the natural antigenicity.The segment rHN2 possesses more linear epitopes exposed on the surface of the native I-IN protein than found in segments rHN3 and rHN1. The hemagglutination activity of segment rHN3 is higher than that of segments rHN2 and rHN1, and partially dependent on the three-dimensional conformation of HN3 protein. Cross-reactivity between rHNs and standard antisera against influenza virus type A, type B suggested that rHNs might not be the best alternative as specific antigens to detect virus in clinicalserum specimens.

Genetic Characterization and Antigenic Analysis of Hemagglutinin-neuraminidase Glycoprotein of Newcastle Disease Virus Isolates / 微生物学通报

Twenty Newcastle disease virus(NDV)strains were isolated from diseased chicken and geese in field outbreaks during 2005 and 2006 in some regions of Jiangsu and Guangxi,and the antigenic analysis of the all NDV isolates had been done based on the reaction spectrum with a panel of monoclonal antibodies to the HN glycoprotein.The entire ORFs encoding HN protein of these NDV isolates were amplified by RT-PCR successfully,cloned and sequenced.The resultant sequences of HN genes of 13 isolates of chicken origin and 7 isolates of goose origin were gained and analyzed.The results of reaction spectrum showed that there were some distinct differences in the antigenic epitopes among the 20 NDV isolates.And the sequences revealed that the coding regions of the HN genes of these isolates all consisted of 1716 nt characteristic of virulent strains of NDV,coding for 571 amino acids.Neucleotides sequence homology were found to be from 94.8%to 100%among 18 NDV isolates of genotypeⅦ,and the neucleotides sequence homology between all the isolates and the other genotypeⅦstrains of recent years in China ranged from 92.1%to 99.6%.The deduced amino acid sequences and the receptor-binding regions of HN proteins between the NDV isolates of chicken origin and of goose origin were compared and analyzed.The results showed that some unique amino acid substitutions were found in the genome of the NDV isolates,and the close genetic similarity provided evidence for epidemiological linkage between the NDV isolates of chicken origin and of goose origin in the same period.

Construction of eukaryotic vector for HN gene of NDV Italien strain and its expression / 解放军医学杂志

Objective To construct an eukaryotic expression plasmid containing gene coding for the hemagglutinin-neuraminidase(HN)of newcastle disease virus(NDV)oncolytic strain Italien,and then to express the protein in eukaryotic cell.Method The HN cDNA was synthesized from viral RNA by RT-PCR,and the eukaryotic expression vector of HN gene(named pcDNA3.1-HN)was constructed.The vector pcDNA3.1-HN was transfected into CHO-K1 cell by liposome,and G418 was used to select stable clones expressing HN gene.The expression of HN protein was visualized by Western blot and Immunofluorescence microscopy.Results Restriction analysis and DNA sequencing proved that HN gene was correctly cloned into expression vector.Western blot analysis and immunofluorescence showed that the HN was expressed in CHO-K1 cells.Conclusion The HN cDNA of NDV was successfully cloned into eukaryotic vector which showed good expression of HN protein in CHO-K1 cells.