Leafhopper salivary carboxylesterase suppresses JA-Ile synthesis to facilitate initial arbovirus transmission in rice phloem

Plant jasmonoyl-L-isoleucine(JA-Ile)is a major defense signal against insect feeding,but whether or how insect salivary effectors suppress JA-Ile synthesis and thus facilitate viral transmission in the plant phloem remains elusive.Insect carboxylesterases(CarEs)are the third major family of detoxification enzymes.Here,we identify a new leafhopper CarE,CarE10,that is specifically expressed in salivary glands and is secreted into the rice phloem as a saliva component.Leafhopper CarE10 directly binds to rice jasmonate resistant 1(JAR1)and promotes its degradation by the proteasome system.Moreover,the direct association of CarE10 with JAR1 clearly impairs JAR1 enzyme activity for conversion of JA to JA-Ile in an in vitro JAIle synthesis system.A devastating rice reovirus activates and promotes the co-secretion of virions and CarE10 via virus-induced vesicles into the saliva-storing salivary cavities of the leafhopper vector and ultimately into the rice phloem to establish initial infection.Furthermore,a virus-mediated increase in CarE10 secretion or overexpression of CarE10 in transgenic rice plants causes reduced levels of JAR1 and thus suppresses JA-Ile synthesis,promoting host attractiveness to insect vectors and facilitating initial viral transmission.Our findings provide insight into how the insect salivary protein CarE10 suppresses host JA-Ile synthesis to promote initial virus transmission in the rice phloem.

Clinical characteristics of patients with COVID-19 presenting with gastrointestinal symptoms as initial symptoms: Retrospective case series

BACKGROUND A large number of pneumonia cases due to coronavirus disease 2019(COVID-19)have been first reported in China.Meanwhile,the virus is sweeping all around the world and has infected millions of people.Fever and pulmonary symptoms have been noticed as major and early signs of infection,whereas gastrointestinal symptoms were also observed in a significant portion of patients.The clinical investigation of disease onset was underestimated,especially due to the neglection of cases presenting with gastrointestinal symptoms.AIM To characterize the clinical features of coronavirus-infected patients with gastrointestinal symptoms as initial symptoms.METHODS This is a retrospective,single-center case series of the general consecutive hospitalized patients with confirmed COVID-19 at Wuhan Union Hospital from February 2,2020 to February 13,2020.According to their initial symptoms,these patients were classified into two groups.Patients in group one presented with pulmonary symptoms(PS)as initial symptoms,and group two presented with gastrointestinal symptoms(GS).Epidemiological,demographic,clinical,laboratory,and treatment data were collected for analysis.RESULTS Among the 50 patients recruited,no patient has been admitted to intensive care units,and no patient died during the study.The duration of hospitalization was longer in the GS group than in the PS group(12.13±2.44 vs 10.00±2.13,P<0.01).All of the 50 patients exhibited decreased lymphocytes.However,lymphocytes in the GS group were significantly lower compared to those in the PS group(0.94±0.06 vs 1.04±0.15,P<0.01).Procalcitonin and hs-CRP were both significantly higher in the GS group than in the PS group.Accordingly,the duration of viral shedding was significantly longer in the GS group compared to the PS group(10.22±1.93 vs 8.15±1.87,P<0.01).CONCLUSION COVID-19 patients presenting with gastrointestinal symptoms as initial symptoms need more days of viral shedding and hospitalization than the patients presenting with pulmonary symptoms.

Evaluation of the Survivability of SARS-CoV-2 on Cardboard and Plastic Surfaces and the Transferability of Virus from Surface to Skin

Objective: To 1) characterize the decay curve of infective SARS-CoV-2 over time on the surface of cardboard packaging and plastic mailer packaging;2) characterize the transferability over time of virus-inoculated cardboard packaging and plastic mailer packaging to skin. Methods: We inoculated samples of plastic and cardboard packaging with a titer of SARS-CoV-2 > 106 TCID50/ mL to evaluate the survivability and transferability to the skin (pig skin) over time. A cell culture-based infectivity assay (TCID50) was used to determine viral titers. Regression analysis was used to characterize decay curves. Results: The time that SARS-CoV-2 remained transferable to skin was reduced on both packaging substrates compared to the total time of survivability, though cardboard demonstrated a substantially larger reduction. Virus inoculated plastic substrates continued to transfer the virus to the skin after 7 hours of holding time and regression analysis predicts this transferability would remain detectable up to 9.5 hours of holding time. Inoculated cardboard substrates demonstrated detectable transfer at 15 minutes of holding time, but no viable virus could be detected on the skin after 30 minutes of holding time. Conclusions: The type of material used as a packaging substrate substantially modifies the potential for SARS-CoV-2 fomite transmission. The use of materials that limit fomite transmission from packaging should be considered among strategies to reduce the transmission of SARS-CoV-2. Future research should investigate the generalizability of these findings for other viral pathogens that potentially transmit via fomite.

Studies on Mucosal Immunity Induced by Transmissible Gastroenteritis Virus Nucleocapsid Protein Recombinant Lactobacillus casei in Mice and Sow

Mucosal immunity plays an important role in protecting pigs against transmissible gastroenteritis virus （TGEV） infection. To elicit mucosal immune response against TGEV, we developed a surface antigen display system using the poly-γ- glutamate synthetase A （pgsA） protein of Bacillus subtilis as an anchoring matrix to express recombinant fusion proteins of pgsA and nucleocapsid protein of TGEV in Lactobacillus casei. Surface location of fusion protein was verified by ELISA and indirect immunofluorescence test. Oral and intranasal inoculations of pregnant sow and mice with recombinant L. casei resulted in high levels of serum immunoglobulin G （IgG） and secretory immunoglobulin A （slgA） against recombinant N protein as demonstrated by ELISA. More importantly, the level of specific slgA in colostrum significantly increased compared with that of IgG. The serum IgG levels of the piglets increased after suckling colostrum produced by sows was previously inoculated with recombinant L. casei. These results indicate that immunization with recombinant L. casei expressing TGEV N protein on its surface elicited high levels of specific slgA and circulating IgG against TGEV N protein.

Genetic diversity of RNA viruses infecting invertebrate pests of rice

Invertebrate species are a natural reservoir of viral genetic diversity,and invertebrate pests are widely distributed in crop fields.However,information on viruses infecting invertebrate pests of crops is limited.In this report,we describe the deep metatranscriptomic sequencing of 88 invertebrate samples covering all major invertebrate pests in rice fields.We identified 296 new RNA viruses and 13 known RNA viruses.These viruses clustered within 31 families,with many highly divergent viruses constituting potentially new families and genera.Of the identified viruses,13 RNA viruses clustered within the Fiersviridae family of bacteriophages,and 48 RNA viruses clustered within families and genera of mycoviruses.We detected known rice viruses in novel invertebrate hosts at high abundances.Furthermore,some novel RNA viruses have genome structures closely matching to known plant viruses and clustered within genera of several plant virus species.Fortyfive potential insect pathogenic RNA viruses were detected in invertebrate species.Our analysis revealed that host taxonomy plays a major role and geographical location plays an important role in structuring viral diversity.Cross-species transmission of RNA viruses was detected between invertebrate hosts.Newly identified viral genomes showed extensive variation for invertebrate viral families or genera.Together,the large-scale metatranscriptomic analysis greatly expands our understanding of RNA viruses in rice invertebrate species,the results provide valuable information for developing efficient strategies to manage insect pests and virus-mediated crop diseases.

Enteric transmission of transfusion-transmitted virus

Objective To detect the virus in the feces and sera of patients in an outbreak of enterically transmitted non-A,non-E hepatitis,and this review covers the epidemiologic features and experimental infection of this novel virus.Data sources Data sources come from our own work on this subject,published and unpublished.Study selection Mainly our own work is included,and related literature is collected.Results In an outbreak of enterically transmitted non-A-E hepatitis among students,a total of 381 cases (60.7%)were documented.Viral fragments identical to transfusion transmitted virus(TTV)were detected in both serum and stool samples.Asymptomatic virus carriers among the staff had positive serum(32.1%)and feces(24.6%),clearly a potential source of infection.This viral infection prevalence in 2 remote villages in northern and southern China was 9.2% and 10.6%,respectively,suggesting that China is an endemic area.In this study,groups of 3 Rhesus monkeys were infected via oral or intravenous inoculation with patient feces.Two additional monkeys were infected by passage.The virus was detected in serum,peripheral blood mononuclear cell(PBMC),liver,spleen and small intestine,while the virus positive single strand,which might be a replicative intermediate,was only in liver,intestine and PBMC of all animals.Conclusions This nonenveloped DNA virus might be transmitted both by blood and enteric routes.Considering its wide distribution and high prevalence,we suppose that nonparenteral transmission is more important.