Dually Labeled Biomolecules for Characterizing Biotinylated Species through Competitive Binding Reactions.

The capability of biotinylated molecules to bind streptavidin may be a more functional measure of the success of target biotinylation than titration of total bound biotins per molecule. It was demonstrated that the binding capability could be assessed by a competitive assay, in which a biotinylated antibody (BA) (or protein, ligand, receptor etc.) of interest competed with a reference antibody (or a protein) dually labeled with biotin and electrochemiluminescence (ECL) moieties for the binding sites of streptavidin coated on the surface of magnetic beads. Inversely related to the ECL signal, the binding capability of a biotinylated antibody can be reproducibly evaluated by multiple sets of easily acquired data series rather than by a single measurement. This method can be employed in an ordinary laboratory with an automated ECL analyzer or other readout instruments for routine characterization of any biotinylated species, such as proteins, ligands, receptors, and polypeptides.

Reconstituting the epidemic history of mono lineage of HIV-1 CRF01_AE in Guizhou province, Southern China.

Guizhou province, located between border provinces and Central province of China, plays a crucial role in the transmission of HIV-1, implying it is important to monitor the epidemic of HIV-1 in this region. Available HIV-1 infected patients' plasma (n=78) were collected from Tongren city, Eastern Guizhou. Full-length gag, partial pol and env gene sequences were amplified and analyzed using phylogenetic, recombinant and Bayesian molecular clock approaches. Phylogenetic and recombinant analyses showed that CRF01_AE predominated among injecting drug users and heterosexuals in Tongren city with 85.9% proportion, it was followed by B' (5.1%), CRF07_BC (3.8%), CRF08_BC (3.8%), and B (1.3%). Moreover, 98.5% of CRF01_AE strains belonged to the distinct lineage CRF01_AE-v previously found in Guangxi province. To infer the most probable origin of CRF01_AE-v in Guizhou province, we download all available full length of CRF01_AE gag, pol and env gene region sequences from China in Los Alamos HIV sequence database. Phylodynamic and phylogeographic analyses revealed that the expanding CRF01_AE-v epidemic in Guizhou province was the result of local epidemic driven by multiple independent introductions of CRF01_AE-v strains from Guangxi province in early 2000s. High prevalence of CRF01_AE in Guizhou province may bridge the epidemic to Central China. It provides a new insight for the understanding of HIV-1 epidemic in Guizhou province and makes the evolutionary history of CRF01_AE in China more intact.

Relatively high prevalence of drug resistance among antiretroviral-naive patients from Henan, Central China.

To elucidate the prevalence of HIV-1 subtypes and transmitted drug resistance in Henan, central China, HIV-1-positive blood samples from 187 antiretroviral-naive patients were collected in our study from August 2009 to November 2010. Subtype B' (92.0%, 172 of 187) remains the predominant HIV-1 subtype in Henan province and was prevalent in all risk populations and geographic regions. Of 98 pol sequences 67 (68.4%) harbored drug resistance mutations, and only 14 (14.3%, 14 of 98) sequences have mutations associated with significantly reduced phenotypic susceptibility to antiretroviral drugs. The unexpectedly high percentage of drug resistance in Henan province is mainly due to the prevalence of minor mutations in the protease and integrase regions, especially A71T/V and L68V/I/IM/LV. In all, we detected a relatively high prevalence of drug resistance with unique mutation distributions among antiretroviral-naive patients from Henan province.

Emergence of a new HIV type 1 CRF01_AE variant in Guangxi, Southern China.

The distribution of HIV-1 subtypes and genetic characterization of CRF01_AE in Guangxi, southern China were identified. The distribution of HIV-1 genotypes based on gag, pol, and partial env sequences (n=349) was as follows: CRF01_AE (66.5%), CRF08_BC (19.2%), CRF07_BC (7.2%), URF (4.6%), subtype B (1.7%), and subtype B' (0.9%). CRF01_AE predominated in all geographic regions and risk populations and there were multiple introductions of CRF01_AE strains in Guangxi. We found a peculiar CRF01_AE monophyletic lineage distinct from other CRF01_AE viruses, and we designated it "CRF01_AE-v" for convenience. CRF01_AE-v circulating in both heterosexuals and injecting drug users (IDUs) had accounted for 39.7% of CRF01_AE. It showed a selective advantage in the Guangxi population and formed its own characteristic compared with all the CRF01_AE references. Our results suggested that CRF01_AE-v was a new variant of CRF01_AE and it might lead to a new epidemic in Guangxi.