OBJECTIVETo characterize HA1 gene of influenza B virus circulated in 1990 through 2000 in China.

METHODSViral RNA was extracted and transcribed into cDNA by reverse transcriptase and amplified by PCR. The product of PCR was purified and sequenced by ABI377. The sequence data were analyzed with epidemic records.

RESULTS1. Two major lineages of influenza B virus always circulated during the period of 1990-2000 in China; the Yamagata lineage was the main lineage, but in 1994 and 1997 the Victoria lineage was more active. 2. During 1992-2000 the Yamagata lineage evolved into two minor groups whose distance in HAI amino acid sequences was about 6%. 3. Large and non-reverse mutators led the development of influenza B epidemics in 1990-2000 in China. 4. Except for a few strains, there was little difference among the influenza B viruses of the same major lineages circulated in the same year in China.

CONCLUSIONSTwo major lineages of influenza B virus always circulated during the period from 1990-2000 in China,and the Yamagata lineage diverged into two minor groups in recent years. Exchanges of the lineages and the appearance of large non-reverse mutators possibly had important epidemic significance.

China ; epidemiology ; Genes, Viral ; genetics ; Influenza B virus ; classification ; genetics ; RNA, Viral ; genetics ; Sequence Analysis ; Sequence Homology, Amino Acid ; Sequence Homology, Nucleic Acid

OBJECTIVETo set up a novel, simple, sensitive, specific, repeatable and rapid assay for diagnosis of influenza.

METHODSMonolayers of MDCK cells were inoculated with the specimens for amplifying viral yield, the feature of receptors on cell surface was changed by treatment of neuraminidases of influenza A and B viruses. Afterward, based on the lectin binds to receptors on cell surface with strict specificity,the phenomenon of red blood cell aggregation was observed under the conventional microscope. Finally, the tested results could be determined by the extent of red blood cell aggregation.

RESULTSThere was a complete (%) consistency rate (100%) for viral isolation between new and routine tests. In general, the results were detected with new assay within 20 h. The sensitivity of new assay was over 100-10,000 times higher than that of routine method. Meanwhile, the novel test could not only be used for rapid diagnosis in the clinic, but also be used for influenza surveillance. The best concentration of red blood cells was 1 in the detection assay. The testing result was not effected by red blood cells taken from either different red blood cell type of human or different individual of guinea pigs.

CONCLUSIONSThe novel method has several advantages: simple, high sensitivity and specificity, accurate and suitable for multiple purposes.

Animals ; Cells, Cultured ; Erythrocyte Aggregation ; drug effects ; Guinea Pigs ; Humans ; Influenza A virus ; enzymology ; isolation & purification ; Influenza B virus ; enzymology ; isolation & purification ; Influenza, Human ; diagnosis ; virology ; Neuraminidase ; analysis ; Reagent Kits, Diagnostic ; Sensitivity and Specificity

BACKGROUNDTo understand the characterization of genome of a strain of avian influenza A H9N2 virus repeatedly isolated from a child with influenza illness. Thereafter to reveal the origin of this H9N2 virus.

METHODSViruses were passed in embryonated hen eggs and virion RNA was extracted from allantoic fluid and reverse transcribed to synthesize cDNA. cDNA was amplified by PCR and the PCR product was purified with a purification kit. Afterwards RNA sequence analysis was performed by dideoxynucleotide chain termination and a cloning method. Finally, phylogenetic analysis of the sequencing data was performed with MegAlign (Version 1.03) and Editseg (Version 3.69) softwares.

RESULTSGenome of A/Guangzhou/333/99 (H9N2) virus was closely related to avian influenza A H9N2 virus, but obvious difference from that of A/Duck/Hong Kong/Y439/97(H9N2) virus, as well as its genome did not include any RNA segment derived from human influenza A virus. However, the genes encoding the HA,NA,NP and NS proteins of A/Guangzhou/333/99 virus were derived from those of G9 lineage virus, the rest genes encoding the M and three polymerase (PB2,PB1 and PA) proteins were derived from G1 lineage strain.

CONCLUSIONSA/Guangzhou/333/99 virus was a reassortant derived from reassortment betweenG9 and G1 lineages of avian influenzaA(H9N2) viruses. Therefore, the most possibility is that it is derived from avian influenza A virus directly. The results do not only demonstrate that avian influenza A (H9N2) virus could infect men, but also firstly prove that the genetic reassortment could be occurred between different genetic lineages of avian influenza A (H9N2) viruses in the nature.

Animals ; Base Sequence ; Chick Embryo ; Child ; Genome, Viral ; Humans ; Influenza A Virus, H9N2 Subtype ; Influenza A virus ; genetics ; Influenza, Human ; virology ; Phylogeny

Objective To evaluate and compare the analytical performances and application values of three nucleic acid extraction methods for quantification of plasma Epstein-Barr Virus ( EBV ) DNA. Methods It used silica membrane spin column , boiling and automated magnetic bead method to extract viral nucleic acid in parallel , and combined real-time fluorescence quantitative PCR assays for quantitative EBV-DNA quantification.The performances of three methods were determined and compared by using the third-party reference materials , and the clinical values were analyzed by pairing detecting 100 NPC patients and 100 healthy subjects in pair .Results The accuracy and imprecision of three methods were all in line with requirements , and the results of clinical samples were linearly correlated . But actually the reproducibility and intermediate imprecision of the magnetic bead method were smaller and stable than those of the spin column method and the boiling method ( all <3％);the limit of detection for the magnetic bead method was 3.334 ×101 IU/ml, better than that of spin column method (4.159 ×101 IU/ml) and boiling method (8.511 ×101 IU/ml);the linear range of the magnetic bead method was 5.4 ×101 -5.4 ×105 IU/ml, slightly wider than that of the boiling method (5.4 ×102 -5.4 ×105 IU/ml); the ability of anti -Hb interference ability of magnetic bead method is better than that of boiling method ;and the positive rate and the mean viral load of the NPC samples measured with the magnetic bead method were significantly higher (95％, 8.342 ×103 IU/ml) than those measured with the spin column method (84％, 4.707 ×103 IU/ml) and the boiling method (78％, 2.571 ×103 IU/ml) ( P all<0.05).Conclusion The automated magnetic bead nucleic acid extraction method offered better analytical performance and higher clinical value for EBV DNA quantification in plasma .

Objective:To explore the imaging rate and diagnostic rate of positioning the fetal conus medullaris by three-dimensional ultrasound method to detect atlantoaxial intervertebral space, comparing it with the traditional two-dimensional and three-dimensional ultrasound methods.Methods:Consecutively 318 singleton fetuses received routine ultrasound screening during the second trimester were enrolled from November 2017 to December 2018 in Shenzhen Luohu People′s Hospital and Shenzhen People′s Hospital. These fetuses included 276 normal cases and 42 abnormal cases. The abnormal group contained 11 cases tethered cords fetuses(tethered cords group) and 31 cases non-tethered fetuses(non-tethered group). A new ultrasound method named detecting atlanto-axial intervertebral space with three-dimensional ultrasound and traditional two-dimensional and three-dimensional ultrasound methods were used to acquire and store the images. The positions of the fetal conus medullaris were analyzed blindly and recorded by three experienced physicians using three different methods with off-line software.Results:①The χ 2 test comparing multiple sample rates was used to compare the imaging acquisition success rate of fetal conus medullaris by three ultrasound methods. The test level was adjusted to be α′=0.05/4=0.0125, the results showed that there were no statistically significant differences between the three methods in the normal group (χ 2=7.39, P=0.025) and the abnormal group (χ 2=5.32, P=0.070). ②The χ 2 test comparing multiple sample rates was used to compare the diagnostic accuracy of fetal conus medullaris position in normal group by three methods, it showed there was no significant difference in the correct rate of conus medullaris position in the normal group (χ 2=2.52, P=0.284). ③The χ 2 test comparing multiple sample rates was used to compare the diagnostic accuracy of the fetal conus medullaris in tethered cord group and non-tethered group using 3 methods, the difference was not statistically significant in tethered cord group (χ 2=1.22, P=0.543), while the difference was statistically significant in non-tethered group(χ 2=9.69, P=0.008). Conclusions:The method of detecting atlanto-axial intervertebral space with three-dimensional ultrasound has a high imaging rate and diagnostic accuracy in positioning the fetal conus medullaris. Positioning of fetal conus medullaris by detecting atlanto-axial intervertebral space with three-dimensional ultrasound is better than traditional two-dimensional and three-dimensional ultrasound in the abnormal non-tethered fetuses, which can provide more valuable information for prenatal diagnosis consultation and prenatal and postnatal care.