Effect of Metofluthrin-Impregnated Spatial Repellent Devices Combined with New Long-Lasting Insecticidal Nets (Olyset® Plus) on Pyrethroid-Resistant Malaria Vectors and Malaria Prevalence: Field Trial in South-Eastern Malawi.

Long-lasting insecticidal nets (LLINs) experience some operational problems that reduce their effectiveness, such as limited spaces for hanging, biting of mosquitoes outdoors, a shift of key biting time from midnight to dawn or dusk, and development of pyrethroid resistance in mosquitoes. The concept of spatial repellency may be a countermeasure to overcome the above issues. The effect of the combined use of metofluthrin-impregnated spatial repellent devices (MSRDs) and LLINs (Olyset® Plus) on malaria prevalence and vector mosquitoes were examined in malaria endemic villages in south-eastern Malawi. The intervention reduced the infection rate in children as well as the number of pyrethroid-resistant vector mosquitoes. To achieve effective malaria control, continued intervention using MSRDs with 2 strips per 10 m2 at 3-month intervals to reduce the density of malaria mosquitoes is recommended.

Hemagglutination mediated by the spike protein of cell-adapted bovine torovirus.

Bovine torovirus (BToV)-Aichi, recently isolated in cultured cells, showed hemagglutination (HA) activity, although the virus has a truncated hemagglutinin-esterase (HE) protein, judging from its gene structure, indicating the existence of another viral protein with HA activity. We examined whether the spike (S) protein possesses HA activity. A BToV antiserum used in this study, reactive to S but not to HE, inhibited HA activity. Furthermore, cells infected with BToV and those expressing S showed hemadsorption (HAD) activity, which was inhibited by the anti-BToV serum; however, HAD activity by expressed HE was not blocked. These data indicate that the S protein of BToV-Aichi is responsible for its HA activity.

Monitoring and characterization of oseltamivir-resistant pandemic (H1N1) 2009 virus, Japan, 2009-2010.

To monitor and characterize oseltamivir-resistant (OR) pandemic (H1N1) 2009 virus with the H275Y mutation, we analyzed 4,307 clinical specimens from Japan by neuraminidase (NA) sequencing or inhibition assay; 61 OR pandemic (H1N1) 2009 viruses were detected. NA inhibition assay and M2 sequencing indicated that OR pandemic (H1N1) 2009 virus was resistant to M2 inhibitors, but sensitive to zanamivir. Full-genome sequencing showed OR and oseltamivir-sensitive (OS) viruses had high sequence similarity, indicating that domestic OR virus was derived from OS pandemic (H1N1) 2009 virus. Hemagglutination inhibition test demonstrated that OR and OS pandemic (H1N1) 2009 viruses were antigenically similar to the A/California/7/2009 vaccine strain. Of 61 case-patients with OR viruses, 45 received oseltamivir as treatment, and 10 received it as prophylaxis, which suggests that most cases emerged sporadically from OS pandemic (H1N1) 2009, due to selective pressure. No evidence of sustained spread of OR pandemic (H1N1) 2009 was found in Japan; however, 2 suspected incidents of human-to-human transmission were reported.

Simplified screening method for detecting oseltamivir resistant pandemic influenza A (H1N1) 2009 virus by a RT-PCR/restriction fragment length polymorphism assay.

The sudden emergence of the pandemic influenza A (H1N1) 2009 virus in early 2009 has resulted in a rapid transmission of this virus worldwide. Within a short time span, sporadic cases infected with this virus that shows oseltamivir resistance have also been reported. These resistant viruses have an amino acid change from histidine to tyrosine at position 275 (H275Y) of the neuraminidase gene. In this study, a reverse transcriptase PCR/restriction fragment length polymorphism (RT-PCR/RFLP) assay was developed to detect the H275Y mutation. Resistant and sensitive viruses could be differentiated using the RFLP patterns. This RT-PCR/RFLP assay is a simple method and also very specific and sensitive for detecting the H275Y mutation of pandemic influenza A (H1N1) 2009 viruses, and can be used in resource-limited settings.

Comparison of selection pressures on the HA gene of pandemic (2009) and seasonal human and swine influenza A H1 subtype viruses.

The 2009 human pandemic influenza (H1N1) virus possesses the HA gene of the H1 subtype. The evolutionary process of the 2009 H1N1 virus remains to be defined. We performed genetic analyses of the HA gene by comparing the 2009 H1N1 virus with seasonal human and swine viruses. We analyzed sequences of 116 2009 H1N1 viruses, and obtained 1457 seasonal H1N1, 365 swine H1, and 1332 2009 H1N1 viruses from the database. Selection pressure for the 2009 H1N1 virus was higher than that for the swine virus and equivalent to that for the seasonal virus. Positions 206 and 264 were found to be positively selected sites. We also identified sites under different selection pressures from the seasonal or swine virus that may be involved in imparting significant biological characteristics. The evolutionary characteristics of the H1 gene of the 2009 H1N1 virus differed from those of seasonal and swine viruses.

Oseltamivir-resistant influenza viruses A (H1N1) during 2007-2009 influenza seasons, Japan.

To monitor oseltamivir-resistant influenza viruses A (H1N1) (ORVs) with H275Y in neuraminidase (NA) in Japan during 2 influenza seasons, we analyzed 3,216 clinical samples by NA sequencing and/or NA inhibition assay. The total frequency of ORVs was 2.6% (45/1,734) during the 2007-08 season and 99.7% (1,477/1,482) during the 2008-09 season, indicating a marked increase in ORVs in Japan during 1 influenza season. The NA gene of ORVs in the 2007-08 season fell into 2 distinct lineages by D354G substitution, whereas that of ORVs in the 2008-09 season fell into 1 lineage. NA inhibition assay and M2 sequencing showed that almost all the ORVs were sensitive to zanamivir and amantadine. The hemagglutination inhibition test showed that ORVs were antigenetically similar to the 2008-09 vaccine strain A/Brisbane/59/2007. Our data indicate that the current vaccine or zanamivir and amantadine are effective against recent ORVs, but continuous surveillance remains necessary.

Differentiation of human influenza A viruses including the pandemic subtype H1N1/2009 by conventional multiplex PCR.

April 2009 witnessed the emergence of a novel H1N1 influenza A virus infecting the human population. Currently, pandemic and seasonal influenza viruses are co-circulating in human populations. Understanding the course of the emerging pandemic virus is important. It is still unknown how the novel virus co-circulates with or outcompetes seasonal viruses. Sustainable and detailed influenza surveillance is required throughout the world including developing countries. In the present study, a multiplex PCR using four primers was developed, which was designed to differentiate the pandemic H1N1 virus from the seasonal H1N1 and H3N2 viruses, to obtain amplicons of different sizes. Multiplex PCR analysis could clearly differentiate the three subtypes of human influenza A virus. This assay was performed using 206 clinical samples collected in 2009 in Japan. Between February and April, four samples were subtyped as seasonal H1N1 and four as seasonal H3N2. All samples collected after July were subtyped as pandemic H1N1. Currently, pandemic viruses seem to have replaced seasonal viruses almost completely in Japan. This is a highly sensitive method and its cost is low. Influenza surveillance using this assay would provide significant information on the epidemiology of both pandemic and seasonal influenza.

Mosquito larvicidal effectiveness of EcoBio-Block S: a novel integrated water-purifying concrete block formulation containing insect growth regulator pyriproxyfen.

EcoBio-Block S, a novel controlled release system (CRS) for the insect growth regulator pyriproxyfen, uses a water-purifying concrete block system (EcoBio-Block) composed of a porous volcanic rock and cement, and it incorporates the aerobic bacterial groups of Bacillus subtilis natto. EcoBio-Block S showed high inhibitory activity against mosquito emergence as well as a water-purifying effect. Chemical analysis and bioassay showed that EcoBio-Block S provides a high-performance CRS that controls the release of pyriproxyfen at low levels according to "zero order kinetics".