Effect of Different Culture Media on the Proliferation of Avian Influenza Virus H9 Subtypes in MDCK Cells

[Objective] To screen the best culture media for the proliferation of avian influenza virus （AIV） H9 subtypes in MDCK cells. [Method] The DMEM containing 10% （V/V） newborn calf serum, low-serum containing medium （ MEM-MD-611 ） and serum-free medium （SFE4Mega） were used to culture the MDCK monolayer ceils, which were then inoculated with different dilutions of AIV H9 subtypes, and the 3 kinds of media were al- so used as the maintenance solution to culture the virus. The cytopathic changes were observed at every 24 h, and the HA titers of the culture su- pernatants were also determined. [ Result] After culturing for 72 -96 h, the HA titers of the serum-free media were higher than that of low-serum culture media, while the HA titers were higher in the low-serum media than in the serum containing media. [ Conclusion] The 3 kinds of media can all used for the proliferation of AIV_ but the low-serum culture medium （MEM-MD-611 ） and serum-free medium （SFE4Meaa3 are preferred.

A duplex RT-PCR assay for detection of H9 subtype avian influenza viruses and infectious bronchitis viruses

H9 s ubtype avian influenza virus（AIV） and infectious bronchitis virus（IBV） are major pathogens circulating in poultry and have resulted in great economic losses due to respiratory disease and reduced egg production. As similar symptoms are elicited by the two pathogens, it is difficult for their differential diagnosis. So far, no reverse transcription-polymerase chain reaction（RT-PCR） assay has been found to differentiate between H9 AIV and IBV in one reaction. Therefore, developing a sensitive and specific method is of importance to simultaneously detect and differentiate H9 AIV and IBV. In this study, a duplex RT-PCR（d RT-PCR） was established. Two primer sets target the hemagglutinin（HA） gene of H9 AIV and the nucleocapsid（N） gene of IBV, respectively. Spec ific PCR products were obtained from all tested H9 AIVs and IBVs belonging to the major clades circulating in China, but not from AIVs of other subtypes or other infectious avian viruses. The sensitivity of the d RT-PCR assay corresponding to H9 AIV, IBV and mixture of H9 AIV and IBV were at a concentration of 1×10^1, 1.5×10^1 and 1.5×10^1 50% egg infective doses（EID_（50）） m L^–1, respectively. The concordance rates between the d RT-PCR and virus isolation were 99.1 and 98.2%, respectively, for detection of samples from H9N2 AIV or IBV infected chickens, while the concordance rate was 99.1% for detection of samples from H9N2 AIV and IBV co-infected chickens. Thus, the d RT-PCR assay reported herein is specific and sensitive, and suitable for the differential diagnosis of clinical infections and survei llance of H9 AIVs and IBVs.

Replication and Pathology of Duck Influenza Virus Subtype H9N2 in Chukar

To investigate the susceptibility of Chukars to duck avian influenza virus H9N2 and explore their role in interspecies transmission of influenza viruses.Chukars were inoculated with duck avian influenza viruses H9N2.

In silico modification of oseltamivir as neuraminidase inhibitor of influenza A virus subtype H1N1

This research focused on the modification of the functional groups of oseltamivir as neuraminidase inhibitor against influenza A virus subtype H1N1.Interactions of three of the best ligands were evaluated in the hydrated state using molecular dynamics simulation at two different temperatures.The docking result showed that AD3BF2 D ligand（N-[（1S,6R）-5-amino-5-{[（2R,3S,4S）-3,4-dihydroxy-4-（hydroxymethyl） tetrahydrofuran-2-yl]oxy}-4-formylcyclohex-3-en-1-yl]acetamide-3-（1-ethylpropoxy）-1-cyclohexene-1-carboxylate） had better binding energy values than standard oseltamivir.AD3BF2 D had several interactions,including hydrogen bonds,with the residues in the catalytic site of neuraminidase as identified by molecular dynamics simulation.The results showed that AD3BF2 D ligand can be used as a good candidate for neuraminidase inhibitor to cope with influenza A virus subtype H1N1.

Monitoring Report of Maternal Antibody of Broiler Avian Influenza Virus H5 Subtype Re-8 Strain

[ Objective ] The paper was to prevent the occurrence of broiler avian influenza virus HS subtype Re-8 strain effectively in the breeding process of broilers. [Method] The maternal antibodies of broilers in Beijing Baochen Hongwang farm were monitored. According to the disappearance law of maternal antibody, the optimal immune time of broiler avian influenza virus H5 subtype Re-8 strain was determined. [ Result] The maternal antibody level of 2-day-old broilers was relatively high, concentrated at 6 log2 -9 log2, and the antibody positive rate was 100%. The maternal antibody level of 8-day-old broilers concentrated at 4 log2 -6 log2, and the antibody positive rate was 100%. The maternal antibody level of 17-day-old broilers concentrated at 0 log2 -3 log2 , and the antibody positive rate was 0. The average maternal antibody level of 24 - 37 days old broilers was 〈 1 log2, and the antibody positive rate was 0. [ Conclusion ] Although the av- erage maternal antibody level of 8-day-old broilers was higher than 5 log2 , 20% of chickens was 4 log2, and maternal antibody could not protect the flock completely. Therefore, the best primary immunization day age of chicks against avian influenza virus was 8 - 10 days of age.

Multiple RT-PCR Detection of H5,H7,and H9 Subtype Avian Influenza Viruses and Newcastle Disease Virus

Objective:This paper focuses on the multiple detection RT-PCR technology of H5,H7,AND H9 subtype avian influenza viruses and Newcastle disease virus,and points out the specific detection methods and detection procedures of avian influenza and Newcastle disease virus.Methods:The genes of Newcastle disease virus carrying out the HA gene sequence of H5,H7 and H9 subtype AIV in GenBank were used to establish a strategy for simultaneous detection of three subtypes of avian influenza virus and Newcastle disease virus.Results:The results showed that the program can detect and distinguish H5,H7 and H9 subtype avian influenza viruses and Newcastle disease virus at one time.Conclusion:Multiple RT-PCR detection method has high detection sensitivity and can detect and determine different subtypes of avian influenza virus and Newcastle disease virus quickly and accurately,therefore,it has a crucial role in the detection and control of avian influenza H5,H7 and H9 subtypes and Newcastle disease.

北京3株H9N2亚型禽流感病毒HA基因的序列分析

[ Objective] The study aimed to understand the genetic characters of H9N2 subtype avian influenza viruses isolated in Belling area. [ Method] HA genes of three H9N2 subtype avian influenza viruses A/Chicken/Beijing/xu/00, A/Chicken/Beijing/bei/00 and A/Chicken/Beijing/ liu/00 were amplified by RT-PCR and then sequenced. [ Result] The results of phylogenetic analysis showed that A/Chicken/Beijing/xu/00, A/ Chicken/Beijing/bei/00 and A/Chicken/Beijing/liu/00 shared the nucleotide homologies of 84.8% （ Dk/HK/Y439/97 ） -98.0% （ Ck/GX17/00 ）, 85.1% （Dk/HK/Y439/97） - 99.1% （ Ck/GXl 7/00）, 90.7% （ Ck/BJ/3/01 ） - 99.1% （Ck/GX17/00） with the isolates from Hongkong and other are- as of Chinese Mainland respectively. At the same time, the analysis of amino acid indicated that the three isolates belonged to low pathogenic H9N2 isolates of avian origin. The 226^th amino acid of them were L （ Leu）, suggesting their high binding affinity to human cells. There were seven glyco- sylation sites in HA protein, five from HA1 and two from HA2. [ Cenclusien] By analysis at molecular level, it could be concluded that A/Chicken/ Beijing/xu/00, A/Chicken/Beijing/bei/00 and A/Chicken/Beijing/liu/00 were low pathogenic H9N2 isolates of avian origin.

Neutralization activity of influenza A virus humanized antibodies against new subtypes of influenza viruses

Antibodies are ideal for controlling the influenza A virus,but their effect on newly emerging strains is unclear.Here,we assessed the neutralization activity of the humanized monoclonal antibodies(mAbs)F10,H98 and H40 against circulating influenza viruses(H5N1,H1N1,H3N2 and H7N7 and new subtypes viruses H5N6 and H7N9).The results showed that all the three humanized mAbs(F10,H98 and H40)displayed different degrees of virus neutralization activities when encountered with different subtypes of influenza viruses.Remarkably,the humanized monoclonal antibody F10 produced higher and broader neutralization titers(range 25–1.56μg/ml)than those of the other two humanized mAbs(H98(range 50–3.12μg/ml),H40(range 50–5.56μg/ml))to against the viruses H5N1,H1N1,H3N2,H7N7,H5N6 and H7N9.This mAb may represent a new class of heterosubtypic neutralizing humanized mAb that could replace vaccines and chemical drugs.

Hospitalized patients with novel influenza A （H1N1） virus infection： Shanghai, June-July 2009

Background From late May 2009, sporadic imported cases of novel influenza A （HIN1） were continuously confirmed in Shanghai, but there were few reports on its clinical presentation in China. The aim of the study was to investigate the demographic and clinical features of the laboratory-confirmed cases and the treatment with oseltamivir. Method We performed a retrospective study in the Shanghai Public Health Clinical Center （SHAPHC）, reviewing the medical records of the laboratory-confirmed patients derived from June 10 to July 20, 2009. Results A total of 156 cases were enrolled, of whom 152 had a history of recent travel. The mean age was 22.6 years and 89 cases （57.1%） were males. The most common symptoms were fever, cough, and sore throat, with children more likely to run a temperature above 38.5℃ than adults. The mean leucocyte count was 5.4×10^9/L, the mean neutrophil count 3.2×10^9/L and the mean lymphocyte count 1.4×10^9/L. Other findings included a normal range or elevated level of C-reactive protein （CRP） and glutamic-pyruvic transaminase and a normal or decreased level of prealbumin; the levels of prealbumin and CRP were significantly lower in the children than in the adults. Fifty-two patients had abnormal chest CT results, with small unilateral or bilateral pulmonary infiltrates, axillary and mediastinal lymphadenopathy and local pleural thickening, while no cases showed symptoms of hypoxia. All the patients received oseltamivir and recovered without complications, but the duration of fever and virus shedding were significantly longer in the children than in the adults. Conclusions Travel-related circulation may be an important reason for the H1N1 epidemic in the non-epidemic areas, and the virus caused mild respiratory symptoms. The infection in children was more severe in terms of prealbumin levels, temperature, the duration of fever and virus shedding. Oseltamivir was effective for H1N1, but more effective in the adults than in the children.

Reduning plus ribavirin display synergistic activity against severe pneumonia induced by H1N1 influenza A virus in mice

OBJECTIVE:To investigate synergistic effect of Reduning(RDN)injection plus ribavirin against severe pneumonia induced by H1 N1 influenza A virus in mice.METHODS:We established a mouse model of severe pneumonia induced by influenza A virus by infecting Balb/c mice with CA07 virus.We randomly assigned the infected mice into four groups,and treated them with normal saline(NS group),RDN(injection,86.6 mg/kg),ribavirin(injection,66.6 mg/kg)or double Ribavirin plus RDN group,the same dosage as used in the single treatments)for 5 d.Lung index and lung pathology were recorded or calculated in terms of the curative effective.Cytokines,NOD-like receptor family pyrin domain containing 3(NLRP3)inflammasome related protein including caspase-associated recruitment domain(CARD)domain Apoptosis-associated speck-like protein containing a caspase recruitment domain(ASC),caspase-1 and NOD-like receptor family,pyrin domain containing 3(NLRP3),and reactive oxygen species were simultaneously investigated.RESULTS:RDN plus ribavirin treatment,not RDN or ribavirin alone,provided a significant survival benefit to the influenza A virus-infected mice.The combination treatment protected the mice against severe influenza infection by attenuating the severe lung injury.The combined treatment also reduced the viral titers in mouse lungs and lung index,downregulated their immunocytokine levels,including IL-1βand IL-18,and down regulated the NLRP3,especially the transcription and translation of caspase-1.Meanwhile NS group had significantly higher reactive oxygen species(ROS)expression which could was dramatically reduced by the treatment of RDN plus ribavirin.CONCLUSION:Our study showed that RDN combined with ribavirin could protect the mice,and reduce the lung immunopathologic damage caused by severe influenza pneumonia.The mechanism could be that it reduced ROS produce and inhibited NLRP3 inflammasome activation so that mainly lower the downstream inflammatory cytokines IL-1βand IL-18.

Bedside chest radiography of novel influenza A （H7N9） virus infections and follow-up findings after short-time treatment

Background Influenza A （H7Ng） virus infections were first observed in China in March 2013.This type virus can cause severe illness and deaths,the situation raises many urgent questions and global public health concerns.Our purpose was to investigate bedside chest radiography findings for patients with novel influenza A （H7Ng） virus infections and the followup appearances after short-time treatment.Methods Eight hospitalized patients infected with the novel influenza A （H7Ng） virus were included in our study.All of the patients underwent bedside chest radiography after admission,and all had follow-up bedside chest radiography during their first ten days,using AXIOM Aristos MX and/or AMX-Ⅳ portable X-ray units.The exposure dose was generally 90 kV and 5 mAs,and was slightly adjusted according to the weight of the patients.The initial radiography data were evaluated for radiological patterns （ground glass opacity,consolidation,and reticulation）,distribution type （focal,multifocal,and diffuse）,lung zones involved,and appearance at follow-up while the patients underwent therapy.Results All patients presented with bilateral multiple lung involvement.Two patients had bilateral diffuse lesions,three patients had unilateral diffuse lesions of the right lobe with multifocal lesions of the left lobe,and the remaining three had bilateral multifocal lung lesions.The lesions were present throughout bilateral lung zones in three patients,the whole right lung zone in three patients with additional involvement in the left middle and/or lower lung zone（s）,both lower and middle lung zones in one patient,and the right middle and lower in combination with the left lower lung zones in one patient.The most common abnormal radiographic patterns were ground glass opacity （8/8）,and consolidation （8/8）.In three cases examined by CT we also found the pattern of reticulation in combination with CT images.Four patients had bilateral and four had unilateral pleural effusion.After a short period of treatment the pneumonia in one patient had significantly improved and three cases demonstrated disease progression.In four cases the severity of the pneumonia fluctuated.Conclusions In patients with influenza A （H7N9） virus infection,the distribution of the lung lesions are extensive,and the disease usually involves both lung zones.The most common imaging findings are a mixture of ground glass opacity and consolidation.Pleural effusion is common.Most cases have a poor short-time treatment response,and seem to have either rapid progressive radiographic deterioration or fluctuating radiographic changes.Chest radiography is helpful for evaluating patients with severe clinical symptoms and for follow-up evaluation.

Influenza A pandemic （H1N1） 2009 virus infection

The clinical spectrum of the 2009 pandemic influenza A （H1N1） infection ranged from self-limited mild illness to progressive pneumonia, or even a fatal outcome. We summarize the clinical manifestations, risk factors for severe and fatal cases, pathologic findings and treatment of this disease in this paper based on current reports from different regions of the world.

Full-length clone and characterization of a human immunodeficiency virus type 1 subtype B' isolated from Hubei Province,China

There are two types of Human Immunodeficiency Virus （HIV）： HIV-1 and HIV-2. HIV-1 dominates epidemics in many different parts of the world, and HIV-2 is principally responsible for the epidemic in westem Africa. In China, Zeng et al have reported the first individual infected with HIV-1 in 1985. And in the 1990s, there was a severe epidemic involving the HIV-1 B＇ strain among people who sold blood and plasma in Henan, Hubei and adjacent provinces. To further study in HIV/AIDS vaccines and HIV-1 drug resistance for people in these regions, we need to construct an infectious HIV-1 B＇ molecular clone which is representative of the virus in these areas. To this end, we have isolated a HIV-1 B＇ virus from a child who was infected with HIV-1 from his mother in Hubei province, and have constructed a full-length clone from this genome.

Characterization of hemagglutinin gene of influenza A virus subtype H9N2

OBJECTIVE: To determine the origin of human influenza A (H9N2) virus and the relationship among H9N2 strains isolated from different hosts, on the basis of molecular biology. METHODS: Viruses 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. RESULTS: The amino acid sequences at the cleavage site between HA1 and HA2 domains of H9N2 viruses isolated in China are R-S-S-R. One pigeon strain contains seven potential glycosylation sites on the HA protein molecule, while all others have eight. There are 2 to 15 differences of amino acid sequences distributed at 24 different positions on the HA protein molecules among six H9N2 viruses. The H9N2 viruses with multiple lineages of HA genes were co-circulating in China recently. CONCLUSION: The highest possibility is that human influenza A (H9N2) virus was derived from Chicken H9N2 virus, and not derived from pigeon H9N2 virus. However, it is still unknown whether the H9N2 virus could transmit from person to person. The H9N2 viruses with multiple lineages of HA genes are co-circulating in China.

Generation and characterization of a cold-adapted attenuated live H3N2 subtype influenza virus vaccine candidate

Background H3N2 subtype influenza A viruses have been identified in humans worldwide, raising concerns about their pandemic potential and prompting the development of candidate vaccines to protect humans against this subtype of influenza A virus. The aim of this study was to establish a system for rescuing of a cold-adapted high-yielding H3N2 subtype human influenza virus by reverse genetics, Methods In order to generate better and safer vaccine candidate viruses, a cold-adapted high yielding reassortant H3N2 influenza A virus was genetically constructed by reverse genetics and was designated as rgAA-H3N2. The rgAA-H3N2 virus contained HA and NA genes from an epidemic strain A/Wisconsin/67/2005 （H3N2） in a background of internal genes derived from the master donor viruses （MDV）, cold-adapted （ca）, temperature sensitive （ts）, live attenuated influenza virus strain A/Ann Arbor/6/60 （MDV-A）. Results In this presentation, the virus HA titer of rgAA-H3N2 in the allantoic fluid from infected embryonated eggs was as high as 1：1024. A fluorescent focus assay （FFU） was performed 24-36 hours post-infection using a specific antibody and bright staining was used for determining the virus titer. The allantoic fluid containing the recovered influenza virus was analyzed in a hemagglutination inhibition （HI） test and the specific inhibition was found. Conclusion The results mentioned above demonstrated that cold-adapted, attenuated reassortant H3N2 subtype influenza A virus was successfully generated, which laid a good foundation for the further related research.

A quantitative RT-PCR assay for rapid detection of Eurasianlineage H10 subtype influenza A virus

Dear Editor,Influenza A viruses(IAVs)are single-stranded,negative sense RNA viruses.IAV subtype is determined on the basis of the viral surface glycoproteins,hemagglutinin(HA),and neuraminidase(NA).To date,18 HA and 11NA subtypes have been reported(Tong et al.,2012).

Pathogenesis of pandemic H1N1 2009 influenza virusinfection and the implication on management

The pandemic H1N12009 influenza virus has caused thefirst influenza pandemic of the 21st century,leading to disproportionate fatalities in the low-risk population despite the generally mild nature of the illness.Advances in science and technology have allowed very detailed study on the pathogenesis of this novel virus,and many have already been published in less than a year after the start of the pandemic.Information generated from cell lines,animal models,and clinical data analysis has provided us with greater understanding of the behavior of this virus and the associated host response.The new knowledge will allow us to formulate scientifically sound and evidence-based management plans.

Emergence of truncated PB1-F2 protein of H3N2 influenza virus during its epidemic period in Jiangsu Province, China

Background PB1-F2 protein has been proven to increase the pathogenicity of influenza A virus （IAV） strains in primary infection and in secondary bacterial infection. It can also regulate the activity of viral polymerase. However, it was shown in another retrospective study that a portion of IAVs do not express full-length PB1-F2 protein during virus development; different kinds of stop codons cause exits in the open reading frames and form PB1-F2 gene products with the corresponding genotypes. Truncated PB1-F2 in human H3N2 IAVs has long been detected in North America but its evolution in China is still unclear. Methods Influenza-like illnesses （ILls） from the whole of Jiangsu Province were collected and inspected to determine the type and subtype of the viruses. A portion of isolates collected in the epidemic period were selected as samples for later whole-genome sequencing, and the exact sequences were determined and analyzed. Results H3N2 influenza virus was one of the epidemical strains which had been prevalent during 2009-2010, in Jiangsu. Five H3N2 isolates with truncated PB1-F2 protein （25aa） were detected in influenza samples from Nanjing and Xuzhou, while seven similar H3N2 isolates were also reported in Niigata, Japan. Conclusion This emergence indicates the possibility that there has been transmission of the H3N2 virus between the two countries.

Potential infections of H5N1 and H9N2 avian influenza do exist in Guangdong populations of China

Background Southeast China is one of the sites of influenza origin. During 2003-2004, nine avian influenza outbreaks took place in Guangdong Province. But no human case was reported. To examine the status of potential human infection by human influenza （H1N1, H3N2） and avian influenza （H5N1, H7N7, H9N2） in the avian influenza epidemic area of Guangdong Province, China, we conducted a seroepidemiologic survey in the people of this area from April to June of 2004.Methods Three out of 9 H5N1 avian influenza affected poultry areas in Guangdong were randomly selected, and the population living within 3 kilometers of the affected poultries were chosen as the survey subjects. One thousand two hundred and fourteen people were selected from 3 villages at random. Human and avian influenza antibody titers were determined by hemagglutination-inhibition （HI） test and microneutralization test （MNT）. Results The positive rate of antibody to H5N1 was 3.03% in the occupational exposure group and 2.34% in general citizens group; that of H9N2 was 9.52% in the occupational exposure group and 3.76% in the general citizens group. Moreover one case in the occupational exposure group was positive for H7N7. One year later, all previously positive cases had become negative except for one H5N1-positive case. Conclusion The observations imply that H5N1 and H9N2 avian influenza silent infections exist in Guangdong populations.

Clinical features of initial cases of 2009 pandemic influenza A （H1N1） in Macao, China

Background The first case of pandemic influenza A （H1N1） virus infection in Macao Special Administrative Region （SAR） of the People＇s Republic of China was documented on June 18, 2009. Subsequently, persons with suspected infection or of contact with suspected cases received screening. All the confirmed cases were hospitalized and treated with oseltamivir. Their clinical features were observed. This may help for better management for later patients and be of benefit to the government of Macao SAR to adjust its strategy to combat the pandemic influenza A （H1N1） virus infection more efficiently. Methods From June to July 2009, the initial 72 cases of influenza A （H1N1） in Macao were hospitalized in Common Hospital Centre S. Januario （CHCSJ）. The infection was confirmed by real-time reverse-transcriptase polymerase chain reaction （RT-PCR）. The clinical features of the disease were closely observed and documented. Oseltamivir was given to all patients within 48 hours after the onset of disease and maintained for 5 days. Results The mean age of the 72 patients was 21 years old. Forty of them were men and 32 were women. The median incubation of the virus was 2 days （1 to 7 days）. The most common symptoms were fever （97.2%） and cough （77.8%）. The rate of gastrointestinal symptoms including nausea, vomiting, and diarrhea was 2.8%. Fever typically lasted for 3 days （1 to 9 days）. The median time from the onset to positive results of real-time RT-PCR was 6 days （3 to 13 days）. After treatment with oseltamivir, most patients became afebrile within 48 hours. Only one aged patient with a history of glaucoma and hypothyroidism was found to have lung infiltration on chest X-ray. Conclusions The initial cases of pandemic influenza A （H1N1） virus infection in Macao SAR showed that most of the infected persons had a mild course. The virus could be detected by real-time RT-PCR within a median of 6 days from the onset. Oseltamivir was effective.