The matrix segment of the "Spanish flu" virus originated from intragenic recombination between avian and human influenza A viruses.

The 1918 Spanish flu virus has claimed more than 50 million lives. However, the mechanism of its high pathogenicity remains elusive; and the origin of the virus is controversial. The matrix (M) segment regulates the replication of influenza A virus, thereby affecting its virulence and pathogenicity. This study found that the M segment of the Spanish flu virus is a recombinant chimera originating from avian influenza virus and human influenza virus. The unique mosaic M segment might confer the virus high replication capacity, showing that the recombination might play an important role in inducing high pathogenicity of the virus. In addition, this study also suggested that the NA and NS segments of the virus were generated by reassortment between mammalian and avian viruses. Direct phylogenetic evidence was also provided for its avian origin.

Rapid detection of foot-and-mouth disease virus using reverse transcription recombinase polymerase amplification combined with a lateral flow dipstick.

Foot-and-mouth disease caused by foot-and-mouth disease virus (FMDV) is one of the most highly contagious diseases of domestic animals, and leads to enormous economic loss. Currently there are two main prevention and control strategies for the disease: eradication of the infected animals in FMDV free countries, and vaccination of the susceptible animals in countries with endemic FMDV infection. Early discovery and diagnosis of the source of infection is therefore integral to the containment of FMDV. In this study, a two-step reverse transcription recombinase polymerase amplification assay combined with lateral flow detection (RPA-LFD) was developed to detect FMDV. With incubation at 38 °C, a region of the 2B gene on the FMDV genome was successfully amplified within 20 min using specific primers and a probe. The amplified RPA product can be visualized on a lateral flow dipstick. The RPA-LFD assay was highly sensitive, detecting down to 10 copies of plasmid DNA. There was no cross-reactivity with other pathogens causing vesicular lesions. In addition, 143 clinical samples were used to compare RPA-LFD with real-time PCR, with 98.6% concordance between the assays. Therefore, the developed RPA-LFD assay provides a rapid, simple, highly promising approach to be used as point-of-care diagnostics in the field.

A permanent host shift of rabies virus from Chiroptera to Carnivora associated with recombination.

Bat virus host shifts can result in the spread of diseases with significant effects. The rabies virus (RABV) is able to infect almost all mammals and is therefore a useful model for the study of host shift mechanisms. Carnivore RABVs originated from two historical host shifts from bat viruses. To reveal the genetic pathways by which bat RABVs changed their host tropism from bats to carnivores, we investigated the second permanent bat-to-carnivore shift resulting in two carnivore variants, known as raccoon RABV (RRV) and south-central skunk RABV (SCSKV). We found that their glycoprotein (G) genes are the result of recombination between an American bat virus and a carnivore virus. This recombination allowed the bat RABV to acquire the head of the G-protein ectodomain of the carnivore virus. This region is involved in receptor recognition and binding, response to changes in the pH microenvironment, trimerization of G proteins, and cell-to-cell transmission during the viral infection. Therefore, this recombination event may have significantly improved the variant's adaptability to carnivores, altering its host tropism and thus leading to large-scale epidemics in striped skunk and raccoon.

An investigation into the potential effects of infrapopulation structure and other sources of sampling error, on population genetic studies of the transmission of Schistosoma japonicum (Trematoda: Digenea).

BACKGROUND: Schistosoma japonicum remains a major challenge to human and animal health. Earlier microsatellite-based studies reported possible definitive-host-specific private alleles within S. japonicum, opening the possibility that different definitive hosts might harbour different parasite strains. Previous investigations have also detected near-identical multilocus genotypes in populations of adult worms - possibly the result of mutations occurring during the asexual (intramolluscan) phase of clonal expansion. Research has also revealed extensive deviations from Hardy-Weinberg Proportions (HWP) and conflicting results among studies. The present study was performed to examine some of the potential effects of infrapopulation structure on microsatellite-based studies of the transmission ecology of S. japonicum. Potential sources of bias considered included organotropic distribution of worms, non-random mating and corrections for clonal expansion. RESULTS: Stool samples from naturally infected hosts were used to infect snails in the laboratory and thereby expose mice. 274 individual worms were typed at seven microsatellite loci. Removal of individuals bearing duplicate MLGs (as a correction for presumed clonal expansion) had an impact on both HWP and organotropic genetic differentiation. The study found no evidence that heterozygote deficiencies were caused by a Wahlund effect. Female-male pairings appeared to be random and there was no evidence for mate choice by heterozygosity. There was some indication that excess heterozygosity, induced by clonal expansion, can offset heterozygote deficiencies caused by small population size or populations fragmented by parasite control efforts. CONCLUSIONS: The view is supported that miracidia are preferable to adult worms in investigations into host-specific parasite lineages. Where adults must be used, extreme care should be taken with regard to sampling if infrapopulations of small animals are compared with those of larger animals; this is because of organotropic patterns in genetic variation and the tendency to sample from different organs in differently sized hosts. As corrections for clones may accentuate signals of population subdivision, corrections should only be made if tests for clonal expansion prove positive. Finally, evidence for heterozygote deficiency caused by small sample size, calls for carefully designed random and comprehensive sampling strategies for S. japonicum in China, where control efforts have greatly fragmented parasite populations.

New genetic mechanism, origin and population dynamic of bovine ephemeral fever virus.

Bovine ephemeral fever virus (BEFV) is a typical species of the genusEphemerovirus in the family Rhabdoviridae. Today, prevailing BEFV can be divided into three phylogeographic lineages, East Asia, Mideast, and Australia. In this study, we provide evidence that the whole East Asia lineage originates from a homologous recombination (HR) between the Mideast and Australia lineages that probably occurred in the 1940s. To our knowledge, HR has not been proposed before as the genetic mechanism of BEFV. According to the HR event and Bayesian estimation, the three BEFV lineages might originate from Africa, and may have spread to Asia and Australia through the Mideast. In addition, the population of the virus may have augmented significantly in the 2000s, suggesting that the risk for outbreaks of BEFV may be high at present.

Epigenetic modification agents improve genomic methylation reprogramming in porcine cloned embryos.

Incomplete DNA methylation reprogramming in cloned embryos leads to low cloning efficiency. Our previous studies showed that the epigenetic modification agents 5-aza-2'-deoxycytidine (5-aza-dC) or trichostatin A (TSA) could enhance the developmental competence of porcine cloned embryos. Here, we investigated genomic methylation dynamics and specific gene expression levels during early embryonic development in pigs. In this study, our results showed that there was a typical wave of DNA demethylation and remethylation of centromeric satellite repeat (CenRep) in fertilized embryos, whereas in cloned embryos, delayed demethylation and a lack of remethylation were observed. When cloned embryos were treated with 5-aza-dC or TSA, CenRep methylation reprogramming was improved, and this was similar to that detected in fertilized counterparts. Furthermore, we found that the epigenetic modification agents, especially TSA, effectively promoted silencing of tissue specific genes and transcription of early embryo development-related genes in porcine cloned embryos. In conclusion, our results showed that the epigenetic modification agent 5-aza-dC or TSA could improve genomic methylation reprogramming in porcine cloned embryos and regulate the appropriate expression levels of genes related to early embryonic development, thereby resulting in high developmental competence.

A phylogeny for the pomatiopsidae (Gastropoda: Rissooidea): a resource for taxonomic, parasitological and biodiversity studies.

BACKGROUND: The Pomatiopsidae are reported from northern India into southern China and Southeast Asia, with two sub-families, the Pomatiopsinae (which include freshwater, amphibious, terrestrial and marine species) and the freshwater Triculinae. Both include species acting as intermediate host for species of the blood-fluke Schistosoma which cause a public health problem in East Asia. Also, with around 120 species, triculine biodiversity exceeds that of any other endemic freshwater molluscan fauna. Nevertheless, the origins of the Pomatiopsidae, the factors driving such a diverse radiation and aspects of their co-evolution with Schistosoma are not fully understood. Many taxonomic questions remain; there are problems identifying medically relevant species. The predicted range is mostly unsurveyed and the true biodiversity of the family is underestimated. Consequently, the aim of the study was to collect DNA-sequence data for as many pomatiopsid taxa as possible, as a first step in providing a resource for identification of epidemiologically significant species (by non-malacologists), for use in resolving taxonomic confusion and for testing phylogeographical hypotheses. RESULTS: The evolutionary radiation of the Triculinae was shown to have been rapid and mostly post late Miocene. Molecular dating indicated that the radiation of these snails was driven first by the uplift of the Himalaya and onset of a monsoon system, and then by late-Pliocene global warming. The status of Erhaia as Anmicolidae is supported. The genera Tricula and Neotricula are shown to be non-monophyletic and the tribe Jullieniini may be polyphyletic (based on convergent characters). Triculinae from northern Vietnam could be derived from Gammatricula of Fujian/Yunnan, China. CONCLUSIONS: The molecular dates and phylogenetic estimates in this study are consistent with an Australasian origin for the Pomatiopsidae and an East to West radiation via Oligocene Borneo-Philippines island hopping to Japan and then China (Triculinae arising mid-Miocene in Southeast China), and less so with a triculine origin in Tibet. The lack of monophyly in the medically important genera and indications of taxonomic inaccuracies, call for further work to identify epidemiologically significant taxa (e.g., Halewisia may be potential hosts for Schistosoma mekongi) and highlight the need for surveys to determine the true biodiversity of the Triculinae.

Treating cloned embryos, but not donor cells, with 5-aza-2'-deoxycytidine enhances the developmental competence of porcine cloned embryos.

The efficiency of cloning by somatic cell nuclear transfer (SCNT) has remained low. In most cloned embryos, epigenetic reprogramming is incomplete, and usually the genome is hypermethylated. The DNA methylation inhibitor 5-aza-2'-deoxycytidine (5-aza-dC) could improve the developmental competence of cow, pig, cat and human SCNT embryos in previous studies. However, the parameters of 5-aza-dC treatment among species are different, and whether 5-aza-dC could enhance the developmental competence of porcine cloned embryos has still not been well studied. Therefore, in this study, we treated porcine fetal fibroblasts (PFF) that then were used as donor nuclei for nuclear transfer or fibroblast-derived reconstructed embryos with 5-aza-dC, and the concentration- and time-dependent effects of 5-aza-dC on porcine cloned embryos were investigated by assessing pseudo-pronucleus formation, developmental potential and pluripotent gene expression of these reconstructed embryos. Our results showed that 5-aza-dC significantly reduced the DNA methylation level in PFF (0 nM vs. 10 nM vs. 25 nM vs. 50 nM, 58.70% vs. 37.37% vs. 45.43% vs. 39.53%, P<0.05), but did not improve the blastocyst rate of cloned embryos derived from these cells. Treating cloned embryos with 25 nM 5-aza-dC for 24 h significantly enhanced the blastocyst rate compared with that of the untreated group. Furthermore, treating cloned embryos, but not donor cells, significantly promoted pseudo-pronucleus formation at 4 h post activation (51% for cloned embryos treated, 34% for donor cells treated and 36% for control, respectively, P<0.05) and enhanced the expression levels of pluripotent genes (Oct4, Nanog and Sox2) up to those of in vitro fertilized embryos during embryo development. In conclusion, treating cloned embryos, but not donor cells, with 5-aza-dC enhanced the developmental competence of porcine cloned embryos by promotion of pseudo-pronucleus formation and improvement of pluripotent gene expression.

Assessing the effect of an integrated control strategy for schistosomiasis japonica emphasizing bovines in a marshland area of Hubei Province, China: a cluster randomized trial.

INTRODUCTION: More than 80% of schistosomiasis patients in China live in the lake and marshland regions. The purpose of our study is to assess the effect of a comprehensive strategy to control transmission of Schistosoma japonicum in marshland regions. METHODOLOGY/PRINCIPAL FINDINGS: In a cluster randomized controlled trial, we implemented an integrated control strategy in twelve villages from 2009 through 2011 in Gong'an County, Hubei Province. The routine interventions included praziquantel chemotherapy and controlling snails, and were implemented in all villages. New interventions, mainly consisting of building fences to limit the grazing area for bovines, building safe pastures for grazing, improving the residents' health conditions and facilities, were only implemented in six intervention villages. Results showed that the rate of S. japonicum infection in humans, bovines, snails, cow dung and mice in the intervention group decreased from 3.41% in 2008 to 0.81% in 2011, 3.3% to none, 11 of 6,219 to none, 3.9% to none and 31.7% to 1.7%, respectively (P<0.001 for all comparisons). In contrast, there were no statistically significant reductions of S. japonicum infection in humans, bovines and snails from 2008 to 2011 in the control group (P>0.05 for all comparisons). Moreover, a generalized linear model showed that there was a higher infection risk in humans in the control group than in the intervention group (OR = 1.250, P = 0.001) and an overall significant downward trend in infection risk during the study period. CONCLUSIONS/SIGNIFICANCE: The integrated control strategy, designed to reduce the role of bovines and humans as sources of S. japonicum infection, was highly effective in controlling the transmission of S. japonicum in marshland regions in China. TRIAL REGISTRATION: Chinese Clinical Trial Registry ChiCTR-PRC-12002405.

Isolation and identification of a novel rabies virus lineage in China with natural recombinant nucleoprotein gene.

Rabies virus (RABV) causes severe neurological disease and death. As an important mechanism for generating genetic diversity in viruses, homologous recombination can lead to the emergence of novel virus strains with increased virulence and changed host tropism. However, it is still unclear whether recombination plays a role in the evolution of RABV. In this study, we isolated and sequenced four circulating RABV strains in China. Phylogenetic analyses identified a novel lineage of hybrid origin that comprises two different strains, J and CQ92. Analyses revealed that the virus 3' untranslated region (UTR) and part of the N gene (approximate 500 nt in length) were likely derived from Chinese lineage I while the other part of the genomic sequence was homologous to Chinese lineage II. Our findings reveal that homologous recombination can occur naturally in the field and shape the genetic structure of RABV populations.

[Survey on Oncomelania snail distribution in sluices in Dongting Lake region].

OBJECTIVE: To investigate the distribution, classification and reformation of all sluices located in the Dongting Lake region, and found out the relationship between irrigation and Oncomelania snail diffusion. METHODS: The information of sluices and their reformation were collected from the local Department of Water Resources and the information of snail conditions collected from the Department of Schistosomiasis Control. The latitude and longitude of each sluice were pinpointed and record with GPSmap76. All the data were analyzed statistically. RESULTS: There were a total of 589 sluices in the Dongting Lake region including 190 Kejinluo sluices (snails might enter through the sluice, 69 were reformed) and 49 Jinluo sluices (snails could enter through the sluice, 8 were reformed). The occurrence rate of snails was higher in water sluice than in drain sluice, and there was a significant difference between them (P < 0.05); the occurrence rate of snails in the sluice was higher when there were snails outside the sluice than when there was no snails outside the sluice, and there was a significant difference between them(P < 0.05). CONCLUSIONS: The main source of snails in the sluice is from the outside of the sluice and irrigation is the main way that snails spread into sluice. The sluices should be reformed effectively, and the snails inside and outside sluice should also be destroyed effectively in order to consolidate the effect of snail control inside the embankment.

[Selection of government instruments in schistosomiasis control services].

From the perspective of public administration and epidemiology, on the combination of the governance cases in the central and local government of China, the author explores ten modes of the provision of public goods and services in schistosomiasis control services, discusses seven main government instruments, and points out its pluralism, complexity and the slight changes of government' s preference. This paper also explores the approach to help the relevant government make schistosomiasis control work more practicable in field.

Schistosomiasis research in the dongting lake region and its impact on local and national treatment and control in China.

Schistosomiasis is a chronic and debilitating parasitic disease that has often been neglected because it is a disease of poverty, affecting poor rural communities in the developing world. This is not the case in the People's Republic of China (PRC), where the disease, caused by Schistosoma japonicum, has long captured the attention of the Chinese authorities who have, over the past 50-60 years, undertaken remarkably successful control programs that have substantially reduced the schistosomiasis disease burden. The Dongting Lake region in Hunan province is one of the major schistosome-endemic areas in the PRC due to its vast marshland habitats for the Oncomelania snail intermediate hosts of S. japonicum. Along with social, demographic, and other environmental factors, the recent completion and closure of the Three Gorges dam will most likely increase the range of these snail habitats, with the potential for re-emergence of schistosomiasis and increased transmission in Hunan and other schistosome-endemic provinces being a particular concern. In this paper, we review the history and the current status of schistosomiasis control in the Dongting Lake region. We explore the epidemiological factors contributing to S. japonicum transmission there, and summarise some of the key research findings from studies undertaken on schistosomiasis in Hunan province over the past 10 years. The impact of this research on current and future approaches for sustainable integrated control of schistosomiasis in this and other endemic areas in the PRC is emphasised.

Identification of a natural human serotype 3 parainfluenza virus.

Parainfluenza virus is an important pathogen threatening the health of animals and human, which brings human many kinds of disease, especially lower respiratory tract infection involving infants and young children. In order to control the virus, it is necessary to fully understand the molecular basis resulting in the genetic diversity of the virus. Homologous recombination is one of mechanisms for the rapid change of genetic diversity. However, as a negative-strand virus, it is unknown whether the recombination can naturally take place in human PIV. In this study, we isolated and identified a mosaic serotype 3 human PIV (HPIV3) from in China, and also provided several putative PIV mosaics from previous reports to reveal that the recombination can naturally occur in the virus. In addition, two swine PIV3 isolates transferred from cattle to pigs were found to have mosaic genomes. These results suggest that homologous recombination can promote the genetic diversity and potentially bring some novel biologic characteristics of HPIV.

[Thought of schistosomiasis control strategy with emphasis on controlling sources of infection in lake and marshland endemic regions].

This paper discusses the issues and suggestions in the implementation of the new schistosomiasis control strategy with emphasis on controlling sources of infection in lake and marshland endemic regions in order to accelerate the implementation of the new control strategy.

Intragenic recombination as a mechanism of genetic diversity in bluetongue virus.

Bluetongue (BT), caused by Bluetongue virus (BTV), is an economically important disease affecting sheep, deer, cattle, and goats. Since 1998, a series of BT outbreaks have spread across much of southern and central Europe. To study why the epidemiology of the virus happens to change, it is important to fully know the mechanisms resulting in its genetic diversity. Gene mutation and segment reassortment have been considered as the key forces driving the evolution of BTV. However, it is still unknown whether intragenic recombination can occur and contribute to the process in the virus. We present here several BTV groups containing mosaic genes to reveal that intragenic recombination can take place between the virus strains and play a potential role in bringing novel BTV lineages.

[ShRNA against NSP4 gene inhibits the proliferation of bovine rotavirus in vitro].

Based on the NSP4 sequence of bovine rotavirus (BRV), the shRNA was designed and synthesized, and a shRNA recombinant lenti-virus vector RNAi-H1-89 was constructed. The recombinant RNAi-H1-89 Lenti-virus was packaged by transfecting the 293T cell with the recombinant vector RNAi-H1-89 and two helper plasmids using lipofectamine, and then used to infect MA104 cells. The MA104 cells were further infected with BRV strain G6 24h post-infection, with the LacZ shRNA recombinant lenti-virus as control. Thirty-six hours later, the CPE of the infected cells was observed under microscope, shRNA of NSP4 gene inhibited CPE in MA104 cell; the shRNA against NSP4 gene also inhibited NSP4 gene expression by RT-PCR, The virus titer in the cell culture supernatant was significant lower compared with the control group. The above results showed that RNAi-H1-89 against NSP4 gene could specifically silence NSP4 gene expression, and inhibit the proliferation of BRV.

[Study on the relationship between the degree of periportal fibrosis, hepatic parenchymatous fibrosis and diameter of portal vein in Schistosoma japonicum infection].

The degree of periportal fibrosis, hepatic parenchymatous fibrosis and the diameter of portal vein in fishermen from highly endemic area of schistosomiasis japonica in Dongting Lake region were measured. The results showed a significant correlation between the degree of periportal fibrosis and parenchymatous fibrosis and the portal venous diameter with a correlation coefficient of 0.375 and 0.332 respectively. The authors consider that the diameter of the portal vein can be used to assess the hepatic morbidity of patients.

[Protective effects of co-immunization with SjCTPI-Hsp70 and interleukin-12 DNA vaccines against Schistosoma japonicum challenge infection in water buffalo].

OBJECTIVE: To induce protective effect of co-immunization with S. japonicum triose-phosphate isomerase fused to heat shock protein 70 (SjCTPI-Hsp70) plasmid and interleukin-12 (IL-12) DNA vaccines against Schistosoma japonicum (Chinese strain) infection in water buffalo. METHODS: Forty-five 8-10 months-old water buffalo from a nonendemic area were divided into three treatment groups each with fifteen buffalo: experimental group A (SjCTPI-Hsp70+IL-12, 300 microg), experimental group B (SjCTPI+IL-12, 300 microg), and control group C (pVAX+IL-12, 300 microg). All buffalo were immunized with a series of 3 intramuscular injections administered once every four weeks. Twenty-eight days postvaccination, water buffalo were percutaneously challenged with 1000 S. japonicum cercariae. Fecal examinations were conducted two days prior, one day prior, and on perfusion day, and the number of hatching miracidia and eggs per gram feces were recorded. Fifty-six days post-infection, the buffalo were sacrificed and perfused via the descending aorta. The recovered adult worms and eggs in liver tissue were counted. RESULTS: Groups A and B showed a worm reduction rate of 51.2% and 41.5% (chi2=1.89, P>0.05)), female worm reduction of 48.9% and 44.7% (chi2=0.35,P>0.05), fecal egg reduction of 52.1% and 38.3% (chi2=3.84,P<0.05), a reduction of miracidia-hatching rate by 52.1% and 33.2% (chi2=7.30, P<0.01), and liver egg reduction of 61.5% and 42.0% (chi2=7.61 , P<0.01), respectively. CONCLUSION: Co-immunization with SjCTPI-Hsp70 and IL-12 DNA vaccines induces protective immunity against S. japonicum in water buffalo.

A double-blind field trial on the effects of artemether on Schistosoma japonicum infection in a highly endemic focus in southern China.

To further strengthen the evidence-base of artemether for the control of schistosomiasis japonica, a randomised controlled trial was carried out in the Poyang Lake region, a highly endemic area in southern China. A total of 783 individuals, aged 6-60 years, were enrolled. They were first given a single oral dose of praziquantel (50 mg/kg). Then, they were randomly assigned oral artemether (6 mg/kg) or placebo, administered once every 2 weeks for 9-11 doses, covering the entire transmission season for Schistosoma japonicum in 2004. Stool examination 1 month after the final dosing revealed eggs of S. japonicum in 3/373 (0.8%) of the artemether recipients and 56/361 (15.0%) in placebo recipients (chi2=53.69, P<0.001). Compared to the baseline, the geometric mean intensity of S. japonicum infection had decreased by 96.1% in the artemether group, and increased by 50.8% in the placebo group. No acute cases of schistosomiasis japonica were observed in the artemether group, whereas three such cases were reported from the placebo group. Compliance with regard to multi-doses of artemether and placebo was 84.9, and 77.9%, respectively. This study confirms that repeated oral artemether produces no drug-related adverse effects, significantly reduces incidence and intensity of patent S. japonicum infection and results in high compliance. Hence it can be used as an additional tool for the control of schistosomiasis japonica in the lake regions of China.