Identification and genetic characterization of equine Pegivirus in China.

In 2013, two new viruses, equine pegivirus (EPgV) and Theiler's disease-associated virus (TDAV), both belonging to the genus Pegivirus within the family Flaviviridae, were identified. To investigate the geographical distribution and genetic diversity of these two viruses in China, we screened EPgV and TDAV infection in imported race horses and Chinese work horses by using reverse-transcription polymerase chain reaction (RT-PCR). EPgV was detected in 10.8 % (8/74) of the total horses tested, with a prevalence of 5.8 and 22.7 % in the race horses and work horses, respectively. No TDAV infection was found. A near full-length genome sequence of EPgV was obtained that showed an identity of 89.5-90.6 % at the nucleotide level and 98.1-98.3 % at the amino acid level with an American strain, C0035, and another Chinese strain, LW/216, respectively. Phylogenetic analysis showed two different clusters of the sequences from the race horses and work horses, indicating a difference in virus origin. Our results demonstrated a higher positive rate of EPgV in the Chinese work horses than in the imported race horses, a moderate genetic diversity of EPgV strains worldwide and possibly no liver pathogenesis for EPgV infection.

Molecular detection and phylogenetic analysis of human parechovirus in individuals with acute diarrhea and healthy controls in Guangzhou, China.

Human parechoviruses (HPeVs) are prevalent in young children; however, their effects are incompletely understood. We investigated the prevalence, genotype distribution, and phylogeny of HPeVs in individuals with diarrhea (n = 430) and healthy controls (n = 93) by the analysis of stool specimens collected from July 2013 to December 2014; 51 (11.86%) and 6 (6.45%) specimens were HPeV positive, respectively. HPeV1A occurred in 28 (6.51%) and 6 (6.45%) individuals with diarrhea and controls, respectively, whereas HPeV1B (3.95%), HPeV3 (0.23%), HPeV4 (0.70%), and HPeV14 (a rare genotype, 0.47%) were only detected in individuals with diarrhea. There was no significant difference in the rate of HPeV detection between the 2 groups; however, the mean age of HPeV infection was significantly lower in males. We conclude that HPeVs may be opportunistic pathogens associated with acute diarrhea. Immunocompromised individuals, such as children aged under 2 years and the elderly, could be vulnerable to HPeV infections.

Diversity and recombination of human parechovirus in children with acute gastroenteritis in Guangzhou, China.

Human parechovirus (HPeV), a member of Picornaviridae family, is a widespread pathogen causing a wide spectrum of diseases. Like other picornaviruses, HPeV genome recombination has been detected. A total of 322 fecal samples were collected from children outpatients in Guangzhou, China, including 42 (13.0%, 42/322) HPeV-positive samples detected in most of the infected children less than two years old. Seven HPeV genotypes (HPeV1, HPeV3, HPeV4, HPeV5, HPeV6, HPeV8 and HPeV14) were detected, among which, HPeV14, a rare genotype, was reported for the first time in children with acute gastroenteritis in China. This study revealed recombination events in eight samples. Clinical profiles did not yield statistical significance between children with HPeV infection alone and cases without pathogens detected. In conclusion, this study demonstrated that HPeV circulated in Guangzhou, China is diverse genetically, which provided evidence of recombination in HPeV in China.

Characterization of severe hand, foot, and mouth disease in Shenzhen, China, 2009-2013.

Hand, foot, and mouth disease (HFMD) is caused by human enteroviruses, especially by enterovirus 71 (EV71) and coxsackievirus A16 (CA16). Patients infected with different enteroviruses show varied clinical symptoms. The aim of this study was to determine whether the etiological spectrum of mild and severe HFMD changed, and the association between pathogens and clinical features. From 2009 to 2013, a total of 2,299 stool or rectal specimens were collected with corresponding patient data. A dynamic view of the etiological spectrum of mild and severe HFMD in Shenzhen city of China was provided. EV71 accounted for the majority proportion of severe HFMD cases and fatalities during 2009-2013. CA16 and EV71 were gradually replaced by coxsackievirus A6 (CA6) as the most common serotype for mild HFMD since 2010. Myoclonic jerk and vomiting were the most frequent severe symptoms. Nervous system complications, including aseptic encephalitis and aseptic meningitis were observed mainly in patients infected by EV71. Among EV71, CA16, CA6, and CA10 infection, fever and pharyngalgia were more likely to develop, vesicles on the hand, foot, elbow, knee and buttock were less likely to develop in patients infected with CA10. Vesicles on the mouth more frequently occurred in the patients with CA6, but less in the patient with EV71. Associations between diverse enterovirus serotypes and various clinical features were discovered in the present study, which may offer further insight into early detection, diagnosis and treatment of HFMD.

Molecular detection of human parechovirus in children with acute gastroenteritis in Guangzhou, China.

Human parechoviruses (HPeVs) are widespread pathogens causing a wide spectrum of diseases. The prevalence and genetic diversity of HPeV in children with acute diarrhea in China is not well known. The purpose of this study was to investigate the epidemiological characteristics of HPeV in Guangzhou, China. A total of 328 stool specimens collected from children under the age of 5 years with acute diarrhea were tested for the presence of HPeV. Of these, 44 (13.4 %, 44/328) were HPeV positive, with the majority of the infected children (97.7 %, 43/44) being younger than two years of age. HPeV was more frequently detected during July and August. The epidemiological profile of co-infections was similar to that observed in a previous study. Six different HPeV genotypes, including HPeV1, -3, -4, -5, -6, and -14, were identified, and of these, HPeV14, a rarely reported genotype, was reported for the first time in children with acute gastroenteritis in China. In summary, this study clearly demonstrated that HPeV circulating in Guangzhou, China, is genetically diverse, including six genotypes, and it provides useful epidemiological data on the features of HPeV infection in this area.

The association between C-159T polymorphism in CD14 gene and susceptibility to tuberculosis: a meta-analysis.

The association between CD14 gene C-159T polymorphism and tuberculosis (TB) susceptibility remains inconclusive. To derive a more precise estimation of the correlation, we performed a meta-analysis summarize the possible at a systematic manner. PubMed, HighWire and ScienceDirect databases covering all papers (up to November 2012) were searched. Statistical analyses were conducted by Rev-Man and STATA. Random- and fixed-effect models were used to estimate pooled odds ratios (ORs) and 95% confidence intervals (CIs), based on between-study heterogeneity. Eight published case-control studies investigating the relationship between C-159T polymorphism in CD14 gene and TB susceptibility were included. Results showed that individuals with T allele have an increased risk of TB compared with those with C allele (OR (95% CI) was 1.52 (1.11, 2.08) for TT vs. TC + CC, P < 0.001; 1.27 (1.01, 1.61) for T vs. C, P = 0.04). When stratified by ethnicity, variant TT homozygote carriers had an 86% increased risk of TB in Asians (OR (95% CI) was 1.86 (1.57, 2.20) for TT vs. TC + CC, P < 0.001), but not in Caucasians (OR (95% CI) was TT vs. TC + CC: OR = 0.78, 95% CI = 0.51-1.21, P = 0.61). This meta-analysis suggests that C-159T polymorphism in CD14 gene is associated with increased risk of TB, especially in Asians, but not in Caucasians.

High prevalence of thalassemia in migrant populations in Guangdong Province, China.

BACKGROUND: The objectives of this study were to estimate the prevalence of thalassemia and to analyze the need for public health services for migrant populations in different cities in Guangdong Province, China. METHODS: A cross-sectional survey was conducted in 21 cities of Guangdong Province. Twenty-three types of a- and ß-globin gene mutations were detected in a total of 14,230 pregnant women and 14,249 husbands. RESULTS: There was a 16.45% prevalence of thalassemia among the 28,479 individuals, and the prevalences of α-, ß-, and combined α-/ß- thalassemia were 12.03%, 3.80%, and 0.63%, respectively. Compared with the native city residents in the province, the migrants from within the province and the immigrants from outside the province had lower prevalences of thalassemia, but the prevalence values were >11%. CONCLUSIONS: The prevalence values for thalassemia gene mutations were high in all three population groups studied in Guangdong Province. The results indicate that all segments of the Guangdong population should be screened for thalassemia.

Highly conserved antigenic epitope regions of hemagglutinin and neuraminidase genes between 2009 H1N1 and seasonal H1N1 influenza: vaccine considerations.

An immunoinformatics study was conducted to determine the highly conserved antigenic epitope regions of hemagglutinin (HA) and neuraminidase (NA) genes in the humoral immunity and CD4+ and CD8+ T cellular immunity between 2009 pandemic H1N1 (pH1N1) and seasonal H1N1 (sH1N1) viruses. It was found that in sH1N1 viruses, 29 epitope regions of HA genes and 8 epitope regions of NA genes which had been experimentally identified, were highly conserved (97.1-100.0%) in the corresponding genes and predictive epitopes of the pH1N1 viruses. The results suggested that highly conserved antigenic epitope regions might act as the basis of common antigenic vaccines against pH1N1 and sH1N1 viruses.

Genetic mutations in influenza H3N2 viruses from a 2012 epidemic in Southern China.

BACKGROUND: An influenza H3N2 epidemic occurred throughout Southern China in 2012. METHODS: We analyzed the hemagglutinin (HA) and neuraminidase (NA) genes of influenza H3N2 strains isolated between 2011-2012 from Guangdong. Mutation sites, evolutionary selection, antigenic sites, and N-glycosylation within these strains were analyzed. RESULTS: The 2011-2012 Guangdong strains contained the HA-A214S, HA-V239I, HA-N328S, NA-L81P, and NA-D93G mutations, similar to those seen in the A/ Perth/16/2009 influenza strain. The HA-NSS061-063 and NNS160-162 glycosylation sites were prevalent among the 2011-2012 Guangdong strains but the NA-NRS402-404 site was deleted. Antigenically, there was a four-fold difference between A/Perth/16/2009 -like strains and the 2011-2012 Guangdong strains. CONCLUSION: Antigenic drift of the H3N2 subtype contributed to the occurrence of the Southern China influenza epidemic of 2012.

Effectiveness of a prevention of mother-to-child HIV transmission program in Guangdong province from 2007 to 2010.

BACKGROUND: To achieve the goal of United Nations of elimination of new HIV infections, a program of prevention of mother-to-child transmission (PMTCT) was launched in Guangdong province. The objective of this study is to evaluate the effectiveness of the PMTCT program. METHODS: The retrospective cross-section analysis was conducted using the data of case reported cards of HIV positive mothers and their infants from 2007 to 2010 in Guangdong province, and 108 pairs of eligible subjects were obtained. We described the data and compared the rates of MTCT by various PMTCT interventions respectively. RESULTS: The overall rate of HIV MTCT was 13.89% (15) among 108 pairs of HIV positive mothers and their infants; 60.19% (65) of the mothers ever received ARVs, 80.56% (87) of infants born to HIV positive mothers ever received ARVs, but 16.67% (18) of the mothers and infants neither received ARVs. Among all the mothers and infants, who both received ARVs, received triple ARVs, mother received ARVs during pregnancy, and both received ARVs and formula feeding showed the lower rates of HIV MTCT, and the rates were 8.06%, 2.50%, 5.77%, and 6.67% respectively. In infants born to HIV positive mother, who received mixed feeding had a higher HIV MTCT up to 60.00%. Delivery mode might not relative to HIV MTCT. CONCLUSIONS: The interventions of PMTCT program in Guangdong could effectively reduce the rate of HIV MTCT, but the effectiveness of the PMTCT program were heavily cut down by the lower availability of the PMTCT interventions.

Change of urinary fluoride and bone metabolism indicators in the endemic fluorosis areas of southern China after supplying low fluoride public water.

BACKGROUND: Few studies have evaluated health impacts, especially biomarker changes, following implementation of a new environmental policy. This study examined changes in water fluoride, urinary fluoride (UF), and bone metabolism indicators in children after supplying low fluoride public water in endemic fluorosis areas of Southern China. We also assessed the relationship between UF and serum osteocalcin (BGP), calcitonin (CT), alkaline phosphatase (ALP), and bone mineral density to identify the most sensitive bone metabolism indicators related to fluoride exposure. METHODS: Four fluorosis-endemic villages (intervention villages) in Guangdong, China were randomly selected to receive low-fluoride water. One non-endemic fluorosis village with similar socio-economic status, living conditions, and health care access, was selected as the control group. 120 children aged 6-12 years old were randomly chosen from local schools in each village for the study. Water and urinary fluoride content as well as serum BGP, CT, ALP and bone mineral density were measured by the standard methods and compared between the children residing in the intervention villages and the control village. Benchmark dose (BMD) and benchmark dose lower limit (BMDL) were calculated for each bone damage indicator. RESULTS: Our study found that after water source change, fluoride concentrations in drinking water in all intervention villages (A-D) were significantly reduced to 0.11 mg/l, similar to that in the control village (E). Except for Village A where water change has only been taken place for 6 years, urinary fluoride concentrations in children of the intervention villages were lower or comparable to those in the control village after 10 years of supplying new public water. The values of almost all bone indicators in children living in Villages B-D and ALP in Village A were either lower or similar to those in the control village after the intervention. CT and BGP are sensitive bone metabolism indicators related to UF. While assessing the temporal trend of different abnormal bone indicators after the intervention, bone mineral density showed the most stable and the lowest abnormal rates over time. CONCLUSIONS: Our results suggest that supplying low fluoride public water in Southern China is successful as measured by the reduction of fluoride in water and urine, and changes in various bone indicators to normal levels. A comparison of four bone indicators showed CT and BGP to be the most sensitive indicators.

Characterization of TCHQ-induced genotoxicity and mutagenesis using the pSP189 shuttle vector in mammalian cells.

Tetrachlorohydroquinone (TCHQ) is a major toxic metabolite of the widely used wood preservative, pentachlorophenol (PCP), and it has also been implicated in PCP genotoxicity. However, the underlying mechanisms of genotoxicity and mutagenesis induced by TCHQ remain unclear. In this study, we examined the genotoxicity of TCHQ by using comet assays to detect DNA breakage and formation of TCHQ-DNA adducts. Then, we further verified the levels of mutagenesis by using the pSP189 shuttle vector in A549 human lung carcinoma cells. We demonstrated that TCHQ causes significant genotoxicity by inducing DNA breakage and forming DNA adducts. Additionally, DNA sequence analysis of the TCHQ-induced mutations revealed that 85.36% were single base substitutions, 9.76% were single base insertions, and 4.88% were large fragment deletions. More than 80% of the base substitutions occurred at G:C base pairs, and the mutations were G:C to C:G, G:C to T:A or G:C to A:T transversions and transitions. The most common types of mutations in A549 cells were G:C to A:T (37.14%) and A:T to C:G transitions (14.29%) and G:C to C:G (34.29%) and G:C to T:A (11.43%) transversions. We identified hotspots at nucleotides 129, 141, and 155 in the supF gene of plasmid pSP189. These mutation hotspots accounted for 63% of all single base substitutions. We conclude that TCHQ induces sequence-specific DNA mutations at high frequencies. Therefore, the safety of using this product would be carefully examined.

Molecular phylogeny of Coxsackievirus A16 in Shenzhen, China, from 2005 to 2009.

Phylogenetic analysis of a Coxsackievirus A16 (CA16) sequence from Shenzhen, China, and other Chinese and international CA16 sequences revealed a pattern of endemic cocirculation of strains of clusters B2a and B2b within subtype B2 viruses. Amino acid evolution and nucleotide variation in the VP1 region were slight for 5 years.

Isolation and phylogenetic characterization of bat astroviruses in southern China.

Astroviruses are associated with acute gastroenteritis of human and many animal species. Recently, two studies have reported that novel astroviruses were found in bats. In order to extensively understand the genetic and phylogenetic characterization of bat astroviruses, we tested fecal samples of nine bat species that were collected at four natural habitats in three areas of southern China. The geographic distributions of the bats involved differed from previous reports. Three out of nine species of bats were observed to harbor astroviruses. These included Miniopterus schreibersii, Scotophilus kuhlii, and Rousettus leschenaultia. Phylogenetic analysis based on amino acid sequences of partial ORFs of astroviruses revealed that the bat astroviruses are not only divergent from previously described human and other animal astroviruses but also show remarkable diversity among themselves. However, five bat astroviruses were phylogenetically related to mink astrovirus, ovine astrovirus, and the recently discovered human astroviruses VA1, VA2, and VA3. The results indicate that astroviruses may have adapted to the Chiroptera, and bats may transmit astroviruses to humans and other animals, or vice versa.

Comparison of reverse transcription loop-mediated isothermal amplification, conventional PCR and real-time PCR assays for Japanese encephalitis virus.

We developed and evaluated a reverse transcription loop-mediated isothermal amplification (RT-LAMP) assay for detecting Japanese encephalitis virus (JEV). The sensitivity of the JEV RT-LAMP assay was in concordance with that of real-time RT-PCR and 10-fold more sensitive than that of conventional RT-PCR, which the detection limit was 24 copies/µl. The JEV RT-LAMP was highly specific, which no cross-reactivity was found with dengue-2 virus, rabies virus, norovirus, astrovirus and human enterovirus 71. The JEV RT-LAMP assay was more simple and less time-consuming compared to the conventional RT-PCR and real-time RT-PCR, which the amplification could be completed in a single tube within 1 h under isothermal conditions at temperature of 63°C. The results suggest that the RT-LAMP assay can be applied as a practical molecular diagnostic tool for JEV infection and surveillance.

Surveillance and risk factors of norovirus gastroenteritis among children in a southern city of China in the fall-winter seasons of 2003-2006.

AIM: Noroviruses (NoVs) are an important cause of acute gastroenteritis but knowledge on the disease burden and epidemiology in children in the developing countries remains limited. In this study, we performed a surveillance of NoV gastroenteritis in children of China to address some of the questions. METHODS: Faecal specimens from children (<5 years of age) at outpatient clinics of the Nan Fang Hospital in Guangzhou, China during the fall-winter seasons in 2003-2006 were tested for rotaviruses (RVs) and NoVs. A questionnaire on clinical records and hygiene habits was collected from each patient. RESULTS: Among 957 stool specimens tested, 488 (51%) specimens were positive for RVs. NoVs were detected in 112 (24%) of the 469 RV negative specimens. The Genogroup II (GII), particularly GII-4, viruses were predominant. No significant difference of clinical symptoms, hospitalisation and patient care expenses were found between children infected with NoVs and RVs. Consumption of uncooked food is a risk for NoV infection. Contact with diarrhoea patients is a suspected risk factor. Cutting nails frequently is a protective factor against NoV infection. CONCLUSIONS: NoVs are an important cause of acute gastroenteritis in children which need special attention of patient care at the clinics in addition to RVs. The awareness of those risk factors may help future disease control and prevention.

Association of Changes in Metabolic Syndrome Status With the Incidence of Thyroid Nodules: A Prospective Study in Chinese Adults.

Although several cross-sectional studies have shown an association of metabolic syndrome (MetS) with nodular thyroid disease, related prospective studies are scarce. This study investigated the association of MetS with thyroid nodule (TN) incidence in Chinese adults, and explored whether the development of or recovery from MetS is associated with changes in the risk of developing TNs. A total of 4,749 Chinese aged 18-65 years were involved in this 6-year prospective study. The association of MetS with TN prevalence was examined. TN-free individuals at baseline (n = 3,133) were further examined. TN incidence rates in groups with different MetS statuses (MetS-free, MetS-developed, MetS-recovery and MetS-chronic) were analyzed. Of all participants, 18.21 and 31.65% had MetS and TNs, respectively. MetS patients had a higher TN prevalence than the non-MetS group (31.08 vs. 19.81% in males, p < 0.01; 59.52 vs. 39.59% in females, p < 0.01). Sex, age and MetS were independent risk factors for TNs. At a median follow up of 5.94 years, the MetS-chronic group (4.37/100 person-years) had a higher risk of TNs (adjusted incidence rate ratio [IRR] = 1.288 [95% CI 1.014-1.636]) compared with the MetS-free group (2.72/100 person-years) in the whole cohort. In males, the MetS-chronic group (3.76/100 person-years) had a higher risk of TNs (adjusted IRR = 1.367 [95% CI 1.017-1.835]) compared with the MetS-free group (2.31/100 person-years). In females, the risk of TNs was significantly higher in the MetS-chronic (6.44/100 person-years) and MetS-developed (6.31/100 person-years) groups compared with the MetS-free group (3.23/100 person-years).

Synovial Fluid Eotaxin-1 Levels May Reflect Disease Progression in Primary Knee Osteoarthritis Among Elderly Han Chinese: A Cross-Sectional Study.

OBJECTIVE: The CC chemokine family member eotaxin-1, also named chemokine C-C motif ligand 11 (CCL11), has been detected in knee osteoarthritis (OA) and could induce breakdown of cartilage matrix. This study was performed to investigate the plasma and synovial fluid eotaxin-1 levels with the disease progression in elderly Han Chinese with primary knee OA. DESIGN: A total of 143 elderly primary knee OA patients and 135 healthy controls were enrolled in the study. The Western Ontario and McMaster Universities Arthritis Index (WOMAC) was performed to evaluate the clinical severity. The radiographic severity was assessed by Kellgren-Lawrence (K-L) grading. Plasma and synovial fluid (SF) eotaxin-1 levels were explored using enzyme-linked immunosorbent assay. The SF levels of matrix metalloproteinase-3 (MMP-3) and interleukin-6 (IL-6) were also examined. RESULTS: Elevated plasma eotaxin-1 levels were found in knee OA patients compared with healthy controls. Eotaxin-1 levels in SF of knee OA patients with K-L grade 4 were significantly elevated compared with those with K-L grades 2 and 3. Meanwhile, knee OA patients with K-L grade 3 had significantly increased SF levels of eotaxin-1 compared with those with K-L grade 2. Plasma eotaxin-1 levels in different K-L grading did not reach significant difference. Eotaxin-1 levels in SF of knee OA patients were significantly associated with disease severity evaluated by KL grading criteria. In addition, eotaxin-1 levels in SF were positively related to clinical severity illustrated by WOMAC as well as biochemical markers MMP-3 and IL-6. CONCLUSIONS: Eotaxin-1 levels in SF instead of plasma, were independently and positively related to the disease severity in elderly knee OA patients. The inhibition of eotaxin-1 and its related signaling pathways may serve as a novel therapeutic approach for OA progression.

Hyperhomocysteinemia Accelerates Acute Kidney Injury to Chronic Kidney Disease Progression by Downregulating Heme Oxygenase-1 Expression.

AIMS: The risk factors promoting acute kidney injury (AKI) to chronic kidney disease (CKD) progression remain largely unknown. The aim of the present study was to investigate whether hyperhomocysteinemia (Hhcy) accelerates the development of renal fibrosis after AKI. RESULTS: Hhcy aggravated ischemia-reperfusion-induced AKI and the subsequent development of renal fibrotic lesions characterized by excessive extracellular matrix deposition. Mechanistically, the RNA binding protein human antigen R (HuR) bound to the 3'-untranslated region (3'-UTR) of heme oxygenase-1 (HO-1) messenger RNA (mRNA). Homocysteine (Hcy) downregulated HuR expression, reduced the binding of HuR to the 3'-UTR of HO-1, and thereafter decreased HO-1 expression. Administration of the HO-1 inducer cobalt protoporphyrin-IX significantly hindered Hhcy-augmented reactive oxygen species production and renal fibrotic lesions. Innovation and Conclusion: These data indicate that Hhcy might be a novel risk factor that promotes AKI to CKD progression. Lowering Hcy level or HO-1 induction might be a potential therapeutic strategy to improve the outcome of AKI.

Stepwise prediction and statistical screening: B-cell epitopes on neuraminidase of human avian H5N1 virus.

The B-cell epitopes of virus are associated with the antiviral drug and the vaccine screening. As the nucleotide sequences of neuraminidase (NA) of stain GD-01-06 were sequenced, we predicted the α-helix and ß-fold structure and the indexes of the flexible regions of secondary structure of NA with methods of the Hydrophilicity plot by Kyte-Doolittle, the Surface probability plot by Emini and the Antigenic index by Jameson-Wolf, and then screened statistically the parameters to predict B-cell epitopes by the Hierarchical cluster and the Bivariate correlation and the quartiles with SPSS 13.0. The impact of variation of amino acids in NA on its epitopes was analyzed. The predictive results were evaluated by Wu's Antigenic Index and SWISS-MODEL. We found that the most possible epitopes on NA were located within or nearby its N-terminal Nos. 120-137, 81-84, 408-415, 273-282, 429-432, 356-368, 46-55, 146-155, 341-350 and 198-209, which were the dominant regions of NA epitopes. Peptide 120-137 including the glycoprotein domain (NGT126-128) was first chosen as the B-cell epitopes on NA. NA in H5N1 strain isolated after 2003 lacked in No. 53 amino acid (I), resulting in an increase in the surface flexible region of NA in GD-01-06 and an enlargement to their epitope regions (VEP46-48 → VEPISNTNFL46-55). Conclusively, prediction of the B-cell epitopes on the NA based on multiple parameters is useful for researches on the molecular immunology and drug screening and immuno-prophylaxis. A deletion of No. 53 amino acid (I) in NA in strain GD-01-06 might increase its antigenicity.