Development of a competitive ELISA method based on VLPs detecting the antibodies of serotype A FMDV.

Foot-and-mouth disease (FMD) is the highly contagious disease of cloven-hoofed animal that brings considerable economic losses to the animal husbandry. So FMD surveillance which relying on accurate diagnosis is important. Most producing the diagnostic antigen of inactivated FMD virus (FMDV) requires facilities with high biosafety. In our previous studies, virus-like particles(VLPs) resembled the structures of natural virus particles. Here, we established a competitive ELISA (cELISA) method for the detection of antibodies against serotype A FMDV based on serotype A FMDV-VLPs. Via detecting different positive serum and negative serum with different titers, and comparing with different commercial ELISA kits. The specificity and sensitivity of the assay were 100 % and 98 %, respectively. The coincidence rate using the PrioCHECK® FMDV Type A antibody ELISA kit and Liquid-phase blocking (LPB) ELISA were 95.30 % and 92.2 %. Repetitive experiments showed that variation coefficient of intra-batch and inter-batch were less than 9 % and 13 %. The result demonstrated that cELISA based on VLPs from prokaryotic system is highly specific, sensitive and reproducible. The cELISA could also be used to assess the immune responses of serotype A FMDV, especially in developing countries.

Complete Genome Sequence of Foot-and-Mouth Disease Virus Serotype O Strain YNTBa from Yunnan Province of China.

YNTBa is a rabbit-passaged attenuated strain of foot-and-mouth disease virus (FMDV) serotype O. Here, we announce the complete genome sequence of YNTBa, which provides data for further studies on replication, virulence, its determinants, and cell and host tropism of YNTBa.

Effect of amino acid mutation at position 127 in 3A of a rabbit-attenuated foot-and-mouth disease virus serotype Asia1 on viral replication and infection.

An amino acid mutation (R127→I) in the 3A non-structural protein of an FMDV serotype Asia1 rabbit-attenuated ZB strain was previously found after attenuation of the virus. To explore the effects of this mutation on viral replication and infection, the amino acid residue isoleucine (I) was changed to arginine (R) in the infectious cDNA clone of the rabbit-attenuated ZB strain by sitedirected mutagenesis, and the R127-mutated virus was rescued. BHK monolayer cells and suckling mice were inoculated with the R127-mutated virus to test its growth property and pathogenicity, respectively. The effects of the R127 mutation on viral replication and virulence were analyzed. The data showed that there was a slight difference in plaque morphology between the R127-mutated and wild-type viruses. The growth rate of the mutated virus was lower in BHK-21 cells and its virulence in suckling mice was also attenuated. This study indicates that the R127 mutation in 3A may play an important role in FMDV replication in vitro and in pathogenicity in suckling mice.

A pilot study of the effect of pressure-driven lidocaine spray on airway topical anesthesia for conscious sedation intubation.

BACKGROUND: Difficult airway remains not only a challenge to the anesthesiologists, but also a life-threatening event to the patients. Awake intubation is the principal choice to deal with difficult airway, and a key point for awake intubation is airway topical anesthesia. Yet, so far there is no ideal topical anesthesia approach for awake intubation. This study aimed at evaluating the effect of pressure-driven (by 10 L/min oxygen flow) lidocaine spray on airway topical anesthesia in order to find a powerful and convenient method for airway topical anesthesia for conscious sedation intubation. METHODS: Thirty adult patients referred for elective surgery under general anesthesia, aged 18 - C60 years and Mallampati class I or II, were recruited for the study. Before topical anesthesia, the observer's assessment of alert and sedation (OAA/S) scale was controlled between 3 and 4 by intravenous midazolam (0.03 mg/kg), propofol (2 mg×kg(-1)×h(-1)) and remifentanil (0.05 µg×kg(-1)×min(-1)). Ten minutes after sedation, topical anesthesia was performed with the pressure-driven lidocaine spray; the driving pressure was achieved by an oxygen flow of 10 L/min. After topical anesthesia, tracheal intubation was performed and the intubation condition was assessed with modified the Erhan's intubation condition score by an experienced anesthesiologist, and a score of less than 10 was considered to be satisfactory. Attempts to intubate the patient were recorded, and the complications such as local anesthetic toxicity, mucosa injury, and respiration depression were also recorded. The mean arterial blood pressure (MAP), heart rate (HR) and pulse oxygen saturation (SpO2) were recorded at different time points before and after intubation. Patients were asked 24 hours after the operation whether they could recall the events during intubation. RESULTS: All patients were intubated at the first attempt, the average intubation condition score was 7.0 ± 1.1, from 6 to 10, satisfied intubation condition. MAP and HR increased significantly but mildly immediately after the tracheal intubation (P < 0.05), and decreased to the pre-intubation level soon after intubation. There were no related complications and patients had no recall of the intubation procedures. CONCLUSIONS: Topical anesthesia with pressure driven 2% lidocaine spray, where pressure is achieved by 10 L/min oxygen flow, can offer satisfactory intubation conditions for conscious sedation intubation.