Search

Aims: Transmission routes of noroviruses, leading aetiological agents of acute gastroenteritis, are rarely verified when outbreaks occur. Since the destination of norovirus particles being firmly captured by microorganisms could be totally different from that of those particles moving freely, microorganisms with natural affinity ligands such as virus-binding proteins would affect the fate of viruses in environment, if such microbial affinity ligands exist. The aim of this study is to identify norovirus-binding proteins (NoVBPs) that are presumably working as natural ligands for norovirus particles in water environments. Methods and Results: NoVBPs were recovered from activated sludge microorganisms by an affinity chromatography technique in which a capsid peptide of norovirus genogroup II (GII) was immobilized. The recovered NoVBPs bind to norovirus-like particles (NoVLPs) of norovirus GII, and this adsorption was stronger than that to NoVLPs of norovirus genogroup I. The profile of two-dimensional electrophoresis of NoVBPs showed that the recovered NoVBPs included at least 7 spots of protein. The determination of N-terminal amino acid sequences of these NoVBPs revealed that hydrophobic interactions could contribute to the adsorption between NoVBPs and norovirus particles. Conclusions: NoVBPs conferring a high affinity to norovirus GII were successfully isolated from activated sludge microorganisms. Significance and Impact of the Study: NoVBPs could be natural viral ligands and play an important role in the NoV transmission.

In order to develop a dose-response model for SARS coronavirus (SARS-CoV), the pooled data sets for infection of transgenic mice susceptible to SARS-CoV and infection of mice with murine hepatitis virus strain 1, which may be a clinically relevant model of SARS, were fit to beta-Poisson and exponential models with the maximum likelihood method. The exponential model (k= 4.1 x l0(2)) could describe the dose-response relationship of the pooled data sets. The beta-Poisson model did not provide a statistically significant improvement in fit. With the exponential model, the infectivity of SARS-CoV was calculated and compared with those of other coronaviruses. The does of SARS-CoV corresponding to 10% and 50% responses (illness) were estimated at 43 and 280 PFU, respectively. Its estimated infectivity was comparable to that of HCoV-229E, known as an agent of human common cold, and also similar to those of some animal coronaviruses belonging to the same genetic group. Moreover, the exponential model was applied to the analysis of the epidemiological data of SARS outbreak that occurred at an apartment complex in Hong Kong in 2003. The estimated dose of SARS-CoV for apartment residents during the outbreak, which was back-calculated from the reported number of cases, ranged from 16 to 160 PFU/person, depending on the floor. The exponential model developed here is the sole dose-response model for SARS-CoV at the present and would enable us to understand the possibility for reemergence of SARS.

Population connectivity of aquatic organisms is an important factor for sustaining the robustness of metapopulation in a basin-scale as well as for interpreting the properties of respective local populations. We examined the genetic structure of 30 Stenopsyche marmorata (Tricoptera) local populations in 4 catchments in South-Central Miyagi Prefecture, Japan using AFLP markers, and evaluated their dispersal pattern. We constructed a dendrogram using q, and found that 7 populations in headwater were isolated from another area in the basins. Although previous studies on S. marmorata adult flight within streams reported most of the females fly upstream along a watercourse after mating, our results indicated high possibility of non-directional adult dispersal due to wind. The results also suggested a strong potential for DNA polymorphic analysis to enhance understanding of the population connectivity and dispersal patterns of aquatic organisms in a basin scale.