Avian influenza viruses preferentially recognize sialosugar chains terminating in sialic acid-␣2,3-galactose (SA␣2,3Gal), whereas human influenza viruses preferentially recognize SA␣2,6Gal. A conversion to SA␣2,6Gal specificity is believed to be one of the changes required for the introduction of new hemagglutinin (HA) subtypes to the human population, which can lead to pandemics. Avian influenza H5N1 virus is a major threat for the emergence of a pandemic virus. As of 12 June 2007, the virus has been reported in 45 countries, and 312 human cases with 190 deaths have been confirmed. We describe here substitutions at position 129 and 134 identified in a virus isolated from a fatal human case that could change the receptor-binding preference of HA of H5N1 virus from SA␣2,3Gal to both SA␣2,3Gal and SA␣2,6Gal. Molecular modeling demonstrated that the mutation may stabilize SA␣2,6Gal in its optimal cis conformation in the binding pocket. The mutation was found in approximately half of the viral sequences directly amplified from a respiratory specimen of the patient. Our data confirm the presence of H5N1 virus with the ability to bind to a human-type receptor in this patient and suggest the selection and expansion of the mutant with human-type receptor specificity in the human host environment.

No abstract

No abstract

Zika virus (ZIKV) is a flavivirus that was first identified in 1947. Initially, the virus was of little concern for health authorities given there were very few casualties among those suffering an infection. As such, only limited studies were performed on ZIKV. Recently, the viral infection has been linked to microcephaly in infants, which has prompted a dramatic increase in scientific interest in ZIKV research, including methods to allow for rapid virus identification. In this work we report the development of a new type of ZIKV electrochemical biosensor based on surface imprinted polymers and graphene oxide composites. The biosensor was used to detect ZIKV by measuring changes in the electrical signal with changing virus concentrations in buffer and serum using standard electrochemical techniques. The detection limit of our method is similar to the detection limit of the real-time quantitative reverse transcription PCR method.

No abstract

No abstract

Rhinacanthin-M, -N and -Q, natural products isolated from the medicinal plant Rhinacanthus nasutus, and 39 novel naphthoquinone esters have been synthesized in excellent yield by esterification of naphthoquinone-3-(propan-3'-ols) with benzoic or naphthoic acids. Almost all the naphthoquinone esters that contain a C-3 hydroxy group showed significant cytotoxicities against KB, HeLa, and HepG2 cell lines. In contrast, ester derivatives lacking the C-3 hydroxy group were inactive to the cancer cell lines. Two methyl substituents on the C-2' of propyl chain conferred more potent cytotoxicity than when there is only one or no methyl group. Naphthoate esters exhibited greater cytotoxicity than benzoate esters. Computer modeling has been done to obtain a first look at the mode of action in connection with these observations.

We investigate whether a molecularly imprinted polymer (MIP) of influenza A H5N1 could be used to help identify molecules capable of binding to, and inhibiting the function of the virus, via either competitive or allosteric mechanisms.