To explore the impact of the history of infection by the influenza A virus subtype H1N1 on secondary infection by the influenza A virus subtype H9N2, pigs non-infected and pre-infected with H1N1 were inoculated with H9N2 in parallel to compare nasal shedding and seroconversion patterns. Unlike pigs without a background of H1N1 infection, nasal shedding was not detected in pigs pre-infected with H1N1. Both groups generated antibodies against H9N2. However, levels of H1N1 antibodies in pigs pre-infected with H1N1 increased quickly and dramatically after challenge with H9N2. Cross-reaction was not observed between H1N1 antibodies and H9N2 viruses. These findings suggest that circulation of the H1N1 virus might be a barrier to the introduction and transmission of the avian H9N2 virus, thereby delaying its adaptation in pigs.
Animals ; Antibodies, Viral ; immunology ; Cross Reactions ; Immune Sera ; immunology ; Influenza A Virus, H1N1 Subtype ; immunology ; physiology ; Influenza A Virus, H9N2 Subtype ; immunology ; Orthomyxoviridae Infections ; blood ; immunology ; Species Specificity ; Swine ; immunology ; virology

Objective To characterize 5 gpl20 sequences from mainly circulating clades in China and expression of their gp120 glycoproteins. Methods gp120 genes were amplified from the PBMCs of 5 HIV-1 infected individuals in different provinces using nest PCR and their DNA sequences were determined. Sequence characteristics were analyzed and gp120 genes were sub-cloned into the mammalian expression vec-tor to produce gp120 glycoproteins. Results Sequence characteristics indicated these sequences belong to the clade Thai-B, CRF_BC and CRF_AE, respectively. There were some conservative N-linked glycosyla-tion sites and primary Furin protease cleavage motifs in the same positions within gp120 amino acid se-quences although these gp120 sequences were categorized into different clades. In comparison with referen-tial strains, amino acids deletions were found in the V1, V2, V4, V5 regions except for the V3 loop; above all, V3 tip motifs of Thai-B exhibited the more polymorphic forms than those of CRF_BC and CRF_AE. These 5 gp120 sequences were cloned into the eukaryotic expression vector and gpl20 glycoproteins were produced successfully. Conclusion Hyper-variable nature of Env should be considered while designing HIV-1 vaccine or test reagent, and gpl20 expression in vitro is helpful to further research on the Env patho-genesis and vaccine development against the mainly circulating HIV-1 isolates in China.

Objective To develop and evaluate the allele-specific real-time PCR(ASPCR) assay for the detection of minor HIV-1 variants. Methods We developed and evaluated the ASPCR assay, using the K103N mutation site as a model system. We constructed plasmids as standards and designed specific and non-specific primers to discriminate the wild-type and mutant plasmids in the real-time PCR using SYBR green as fluorescence reporter. And then we evaluated the sensitivity, accuracy, reproducibility of ASPCR assay and detected the control samples. Results The specific primer can discriminate the wild-type and mutant plasmids including resistant mutation successfully. The sensitivity of ASPCR assay can achieve less than 0.01% and the accuracy of this method is down to 0.1%. The Intra-assay coefficient of variation is less than 0.7 and the Inter-assay coefficient of variation is less than 1.6. Conclusion ASPCR is a sensitive, accurate and rapid method to detect the minor HIV-1 variants which have resistant mutations and it can be used widely in HIV research. ASPCR also can provide earlier and more resistant information to the clinical therapy.

ObjectiveTo evaluate the sensitivity and accuracy of an in-house detecting method of HIV-1 genotypic drug resistance system. MethodsTotally 130 serum specimens from Henan and Guangxi province were collected from April 2004 to October 2008 and tested in the Military HIV Testing Center of China. ViroSeqTM v2.0 (Abbott, Switzerland), a US FDA approved HIV genotypic drug resistance detecting system was utilized as the reference method. All the specimens were detected by the novel in-house method and the reference method to validate the difference in amplifying efficiency, drug resistance mutation detection and drug resistance report. ResultsConcerning the 14 850 known drug resistance mutation sites,14 752 (99. 3％ ) mutations can be detected by both of the two methods. Rates of concordance of detection in the regions of protease inhibitors-, reverse transcriptase inhibitors- and both two classes inhibitors-resistance were99.7％ ( Kappa =0. 909 9 , P ＜0. 01 ) , 99. 0％ (Kappa=0.952 1, P＜0. 01) and99.3％ (Kappa=0. 948 8, P ＜ 0. 01 ) respectively. Drug resistance reports from these two systems showed similar results (Kappa = 0. 637 4, P ＜ 0. 01 ). The in-house detecting system identified 34 novel mutations besides the ViroSeqTM drug resistance mutation database ( ViroSeqTM software v2. 7). Two mutations, V179F and K238T,had significant effect on HIV drug resistance. ConclusionsThe in-house genotyping system is an accurate,cost-effective method and has a high concordance with commercial ViroSeqTM genotyping system. Database from the in-house assay was superior to this of the ViroSeqTM assay.

Objective To evaluate the antiretroviral therapy(ART),analyze the prevalence of resistance in rural areas,Henan,and explore the presence of minor resistant variants in pre-ART.Methods One hundred and forty-nine AIDS patients initiating ART were recruited and investigated at intervals of 6 months. Method of In-house developed by our laboratory for genotypjc resistance test was to analyze the occurrence of resistance among the failure of ART,and the allele-specific real.time PCR(ASPCR)was used to detect the minor resistant variants at the baseline samples once the resistance occurred.Results Vimlload significantly decreased among the patients who received ART(t=275,P=0.0001),but the absolute counts of CD4+T lymphocytes had no significant change(t=1.765 168,P=0.0852).Rate of resistance among the patients of treatment failure was 4.88%.The result of ASPCR in the survey of baseline showed that the minor resistant variants of M184V were detected in 7 patients and mutation K103N presented in 5 patients.Conclusion The primary drug-resistant straias in the untreated patients were found in Henan,and they might develop the dominant resistance strains and bring about the failure of ART.

Objective To isolate stable passage primary HIV-1 drug resistant strains and observe replication dynamics of the drug resistant isolates and evolvement tendency of the drug resistant mutations in vitro.Methods Peripheral blood mononuclear cells(PBMCs)from 15 AIDS patients receiving highly active antiretroviral therapy(HAART)were collected,and the primary HIV-1 stains were separated utilizing co-cultivated with PBMCs from normal people.HIV-1 pol genes from those strains were obtained by RT-PCR and sequenced.The drug resistant mutations were analyzed in the Stanford HIV Drug Resistance Database.Results Eight strong positive strains were isolated from 15 AIDS patients with viral loads higher than 1000 copies/ml,and two of them were drug resistant.Drug resistant mutations of the two strains were respectively K103N/K238T and M184V/K103N/Y181C/H221Y which show high-level resistance to NVP and 3TC/NVP,respectively.K103N,M184V,Y181C and H221Y exist stably in the environment without drug pressure,however,RT K238T reverted to K238.Conclusion Two drug resistant strains were successfully isolated in vitro without drug pressure.Strains with K103N shows superior fitness and can exist steadily.Strains with M184V and K103N/Y181C/H221Y can also replicate stably in vitro without drug pressure.NNRTI mutation K238T reproduces astatically,which suggests that RT 238 codon might revert gradually to wild genotype.

Neutralizing antibodies are considered to be an important protective parameter used in HIV-l vaccine evaluation.However,the exact role that neutralizing antibodies plays in controlling the disease progression of HIV-1 infected peoples is still undetermined.In this paper,we compared the protective function of the neutralizing antibody response in the plasma from LTNP and TP against clade B and clade C pseudoviruses.No difference in the neutralizing activities between the plasma from LTNP and TP was found,which was consistent with the most recent reports.In addition,no correlations between the titer or breadth and CD4+ or viral load in HIV-1 infected individuals were found.The protective roles played by neutralizing antibodies in controlling disease progression of HIV-1 infected people need to be considered in a new viewpoint.