Our results indicate that NHPs that have contact with humans can be naturally infected with seasonal endemic human infl uenza viruses and with emerging pandemicrisk avian infl uenza viruses. We found serologic evidence of infection in several countries, contexts, and macaque species. Preliminary real-time reverse transcription PCR results also pointed to the presence of virus in a buccal swab from an adult macaque from Cambodia, indicating active infection at the time of sampling. On the basis of results from this study, it seems that pet, performing, and free-ranging macaques are susceptible to infl uenza virus infection. Given the close relationship between humans and NHPs in areas of the world where avian and human infl uenza viruses cocirculate, further surveillance of these populations is warranted. The ability to detect and eventually isolate strains of infl uenza virus currently infecting NHPs and humans at the animal-human interface is paramount to understanding how NHP-human interactions can affect the genetics, transmission, and public health risk for infection with infl uenza A viruses. Label-Free Electrochemical Diagnosis of Viral Antigens with Genetically Engineered Fusion Protein We have developed a simple electrochemical biosensing strategy for the label-free diagnosis of hepatitis B virus (HBV) on a gold electrode surface. Gold-binding polypeptide (GBP) fused with single-chain antibody (ScFv) against HBV surface antigen (HBsAg), in forms of genetically engineered protein, was utilized. This GBP-ScFv fusion protein can directly bind onto the gold substrate with the strong binding affinity between the GBP and the gold surface, while the recognition site orients toward the sample for target binding at the same time. Furthermore, this one-step immobilization strategy greatly simplifies a fabrication process without any chemical modification as well as maintaining activity of biological recognition elements. This system allows specific immobilization of proteins and sensitive detection of targets, which were verified by surface plasmon resonance analysis and successfully applied to electrochemical cyclic voltammetry and impedance spectroscopy upto 0.14 ng/mL HBsAg. In recent years, various types of biosensors have been increasingly becoming practical and useful tools in a wide variety of analytical devices [1, 2] . The immobilization of biological elements to realize the biosensor is an essential step for the successful construction of a diagnostic system. In order to allow the detection of a small amount of target sample and improve detection performance, bioreceptor proteins must be immobilized onto biosensor chip surfaces with high density and nonspecific adsorption avoided or at least minimized. Moreover, orientation control with retention of protein conformation and activity is a required task to be established [3] . One method involves the physical adsorption via van der Waals forces, ionic binding or hydrophobic and polar forces on an insoluble matrix. This is a simple process which causes little disruption of the proteins, while it is unstable during the binding procedure due to the highly dependency against environmental conditions in maintaining its functional characteristics. Thus, the resulting receptor layer seems to form heterogeneous and random orientation. Another method can also be constructed by crosslinking functional reagents by a certain number of functional groups due to its simple procedure and strong chemical bond of proteins. This is widely used for stabilization of proteins that are covalently bound onto the support platform generated by chemical treatment. However, this method has also disadvantages as follows: the difficulty in controlling the crosslinking reaction, the gelatinous nature of the proteins and the relatively low activity of the proteins due to the specific structural features [3, 4] . In each of these methods used for the favorable performance of biosensors, a number of factors deserve careful consideration for strong binding forces between the solid surface and recognition elements, exposure of active sites on the target sample, conservation of biological activity after immobilization process, and simple protocol [3, 4] .