The fall armyworm,Spodoptera frugiperda,which destroys many economic crops such as rice and maize,has recently invaded China.Insect viruses as biological control agents play important roles in killing pests.One potent...The fall armyworm,Spodoptera frugiperda,which destroys many economic crops such as rice and maize,has recently invaded China.Insect viruses as biological control agents play important roles in killing pests.One potential viral insecticide is the environmentally highly infective and virulent densovirus.We successfully rescued Junonia coenia densovirus(JcDV)using its infectious clone in different insect cell lines and larvae of three insect species.Results showed that the lysate of cultured insect cells transfected by the JcDV infectious clone killed the 2 nd instar S.frugiperda.The LD50 of homogenate from JcDV-infected Spodoptera litura to the 2 nd instar S.frugiperda(1.76×10^(8)viral genome copies per larva during 10 d post infection)was higher than that of the 2 nd instar S.litura(7.39×10^(7)Jc DV genome copies)or Helicoverpa armigera larvae(9.71×10^(7)JcDV genome copies).The LT50 of the S.litura homogenate(2.60×10^(9)viral genome copies each larva)to the 2 nd instar S.frugiperda was 6.96 d,longer than that of the S.litura(6.18 d)or the 2 nd instar H.armigera(5.94 d).JcDV could infect the fat body of H.armigera,but not S.frugiperda or S.litura.Although JcDV can infect all three lepidopteran species,their susceptibility to the virus differs.JcDV has great potential as a biological control agent against pests such as S.frugiperda.展开更多
The gene of the non-structure protein 2 （NS2） was cloned by PCR from the genome ofBombyx mori densovirus Zhenjiang strain （BmDNV-Z）, inserted into prokaryotic expression vector pET28a to construct recombinant plas...The gene of the non-structure protein 2 （NS2） was cloned by PCR from the genome ofBombyx mori densovirus Zhenjiang strain （BmDNV-Z）, inserted into prokaryotic expression vector pET28a to construct recombinant plasmid pET28a-NS2 and then expressed in bacteria Escherichia coli BL21 （DE3）. The expressed recombinant protein was identified by SDS-PAGE and Western blot analysis. Then, the recombinant protein was purified by Ni-NTA column, renatured and tested for enzyme activities. The purified NS2 protein exhibited a helicase activity unwinding double-stranded DNA substrates into single-strand primers, and higher unwinding activity to polarity substrate. Similarly, the purified NS2 protein possessed an ATPase activity and its enzyme activity was 0.276 μmol gg^-1 h^-1 in this study. The results indicated that the non- structure protein which encoded by the gene of BmDNV-Z NS2 possesses the biological activities of helicase and ATPase, and the helicase prefers to polarity substrates. Based on these results, it is speculated that the gene of BmDNV-Z NS2 plays an important role in the viral DNA replication.展开更多
In a tritrophic context of plant-insect-entomopathogen,plants play important roles in modulating the interaction of insects and their pathogenic viruses.Currently,the influence of plants on the transmission of insect ...In a tritrophic context of plant-insect-entomopathogen,plants play important roles in modulating the interaction of insects and their pathogenic viruses.Currently,the influence of plants on the transmission of insect viruses has been mainly studied on baculoviruses and some RNA viruses,whereas the impact of plants on other insect viruses is largely unknown.Here,we identified a new densovirus infecting the green peach aphid Myzus persicae and tested whether and how host plants influence the transmission of the aphid densovirus.The complete single-stranded DNA genome of the virus,M.persicae densovirus 2,is 5727 nt and contains inverted terminal repeats.Transcription and phylogenetic analysis indicated that the virus was distinct from other a few identified aphid densoviruses.The virus abundance was detected highly in the intestinal tract of aphids,compared with the lower level of it in other tissues including head,embryo,and epidermis.Cabbage and pepper plants had no obvious effect on the vertical transmission and saliva-mediated horizontal transmission of the virus.However,the honeydew-mediated horizontal transmission among aphids highly depended on host plants(65%on cabbages versus 17%on peppers).Although the virus concentration in the honeydew produced by aphids between 2 plants was similar,the honeydew production of the infected aphids reared on peppers was dramatically reduced.Taken together,our results provide evidence that plants influence the horizontal transmission of a new densovirus in an aphid population by modulating honeydew secretion of aphids,suggesting plants may manipulate the spread of an aphid-pathogenic densovirus in nature.展开更多
Background Dengue virus(DENV)is a major public health threat,with Aedes albopictus being the confrmed vector responsible for dengue epidemics in Guangzhou,China.Mosquito densoviruses(MDVs)are pathogenic mosquitospecif...Background Dengue virus(DENV)is a major public health threat,with Aedes albopictus being the confrmed vector responsible for dengue epidemics in Guangzhou,China.Mosquito densoviruses(MDVs)are pathogenic mosquitospecifc viruses,and a novel MDV was previously isolated from Ae.albopictus in Guangzhou.This study aims to determine the prevalence of MDVs in wild Ae.albopictus populations and investigate their potential interactions with DENV and impact on vector susceptibility for DENV.Methods The prevalence of MDV in wild mosquitoes in China was investigated using open access sequencing data and PCR detection in Ae.albopictus in Guangzhou.The viral infection rate and titers in MDV-persistent C6/36 cells were evaluated at 12,24,48,72,96,and 120 h post infection(hpi)by indirect immunofuorescence assay(IFA)and real time quantitative PCR(RT-qPCR).The midgut infection rate(MIR),dissemination rate(DR),and salivary gland infection rate(SGIR)in various tissues of MDV-infected mosquitoes were detected and quantifed at 0,5,10,and 15 days post infection(dpi)by RT-PCR and RT-qPCR.The chi-square test evaluated dengue virus serotype 2(DENV-2)and Aedes aegypti densovirus(AaeDV)infection rates and related indices in mosquitoes,while Tukey’s LSD and t-tests compared viral titers in C6/36 cells and tissues over time.Results The results revealed a relatively wide distribution of MDVs in Aedes,Culex,and Anopheles mosquitoes in China and an over 68%positive rate.In vitro,signifcant reductions in DENV-2 titers in supernatant at 120 hpi,and an appar‑ent decrease in DENV-2-positive cells at 96 and 120 hpi were observed.In vivo,DENV-2 in the ovaries and salivary glands was frst detected at 10 dpi in both monoinfected and superinfected Ae.albopictus females,while MDV super‑infection with DENV-2 suppressed the salivary gland infection rate at 15 dpi.DENV-2 titer in the ovary and salivary glands of Ae.albopictus was reduced in superinfected mosquitoes at 15 dpi.Conclusions MDVs is widespread in natural mosquito populations,and replication of DENV-2 is suppressed in MDVinfected Ae.albopictus,thus reducing vector susceptibility to DENV-2.Our study supports the hypothesis that MDVs may contribute to reducing transmission of DENV and provides an alternative strategy for mosquito-transmitted disease control.展开更多
The three-dimensional structure of capsid of Aedes albopictus C6/36 densovirus was determined to 14- resolution by electron cryomicroscopy and computer reconstruction. The triangulation number of the capsid is 1. Ther...The three-dimensional structure of capsid of Aedes albopictus C6/36 densovirus was determined to 14- resolution by electron cryomicroscopy and computer reconstruction. The triangulation number of the capsid is 1. There are 12 holes in each triangular face and a spike on each 5-fold vertex. The validity of the capsid and nucleic acid densities in the reconstructions was discussed.展开更多
Parvoviridae is a family of the smallest viruses known with a wide variety of hosts. The capsid structure of the Aedes albopictus C6/36 cell densovirus (C6/36 DNV) at 1.2-nm resolution was obtained by elec-tron cryomi...Parvoviridae is a family of the smallest viruses known with a wide variety of hosts. The capsid structure of the Aedes albopictus C6/36 cell densovirus (C6/36 DNV) at 1.2-nm resolution was obtained by elec-tron cryomicroscopy (cryoEM) and three-dimensional (3D) image reconstruction. Structure compari-sons between the C6/36 DNV and other parvoviruses reveal that the degree of structural similarity be-tween C6/36 DNV and the human parvovirus B19 is higher than that between C6/36 DNV and other in-sect parvoviruses. The amino acid sequence comparisons of structural and non-structural proteins also reveal higher levels of similarity between C6/36 DNV and parvovirus B19 than those between C6/36 DNV and other parvoviruses. These findings indicate that C6/36 DNV is closely related to the human virus B19, and the former might evolve from the human species other than from other insect viruses.展开更多
We have cloned the replicative form of the Periplaneta fuliginosa densonucleosis virus (PfDNV) genome and determined its complete sequence. The sequence has 5 454 nucleotides (nt), the genome consists of an internal u...We have cloned the replicative form of the Periplaneta fuliginosa densonucleosis virus (PfDNV) genome and determined its complete sequence. The sequence has 5 454 nucleotides (nt), the genome consists of an internal unique sequence flanked by inverted terminal repeats (201 nt). The first 122 nt at the 5’end and the terminal 122 nt at the 3’end of both plus and minus strands can fold into a typical hairpin structure. The genome contains seven major open reading frames (ORFs). The plus strand has 4 ORFs occupying the 5’half of the plus strand, whereas the others span the 5’ half of the minus strand. Two potential promoters were found at map units (m.u.) 3 and 97. Computer analysis of sequence homologies with other parvoviruses suggests that the plus strand of Pf DNV encodes very likely the nonstructural proteins and the minus strand probably encodes the structural proteins.展开更多
基金supported by the National Key R&D Program of China(2017YFD0200400)the Natural Science Foundation of Hubei Province,China(2017CFB241)。
文摘The fall armyworm,Spodoptera frugiperda,which destroys many economic crops such as rice and maize,has recently invaded China.Insect viruses as biological control agents play important roles in killing pests.One potential viral insecticide is the environmentally highly infective and virulent densovirus.We successfully rescued Junonia coenia densovirus(JcDV)using its infectious clone in different insect cell lines and larvae of three insect species.Results showed that the lysate of cultured insect cells transfected by the JcDV infectious clone killed the 2 nd instar S.frugiperda.The LD50 of homogenate from JcDV-infected Spodoptera litura to the 2 nd instar S.frugiperda(1.76×10^(8)viral genome copies per larva during 10 d post infection)was higher than that of the 2 nd instar S.litura(7.39×10^(7)Jc DV genome copies)or Helicoverpa armigera larvae(9.71×10^(7)JcDV genome copies).The LT50 of the S.litura homogenate(2.60×10^(9)viral genome copies each larva)to the 2 nd instar S.frugiperda was 6.96 d,longer than that of the S.litura(6.18 d)or the 2 nd instar H.armigera(5.94 d).JcDV could infect the fat body of H.armigera,but not S.frugiperda or S.litura.Although JcDV can infect all three lepidopteran species,their susceptibility to the virus differs.JcDV has great potential as a biological control agent against pests such as S.frugiperda.
基金supported by the National Basic Research Program of China (2005CB121004)
文摘The gene of the non-structure protein 2 （NS2） was cloned by PCR from the genome ofBombyx mori densovirus Zhenjiang strain （BmDNV-Z）, inserted into prokaryotic expression vector pET28a to construct recombinant plasmid pET28a-NS2 and then expressed in bacteria Escherichia coli BL21 （DE3）. The expressed recombinant protein was identified by SDS-PAGE and Western blot analysis. Then, the recombinant protein was purified by Ni-NTA column, renatured and tested for enzyme activities. The purified NS2 protein exhibited a helicase activity unwinding double-stranded DNA substrates into single-strand primers, and higher unwinding activity to polarity substrate. Similarly, the purified NS2 protein possessed an ATPase activity and its enzyme activity was 0.276 μmol gg^-1 h^-1 in this study. The results indicated that the non- structure protein which encoded by the gene of BmDNV-Z NS2 possesses the biological activities of helicase and ATPase, and the helicase prefers to polarity substrates. Based on these results, it is speculated that the gene of BmDNV-Z NS2 plays an important role in the viral DNA replication.
基金This work was supported by Ministry of Education of the People's Republic of China Chinese Universities Scientific Fund(No.Z1090121096,NWAFU)Ministry of Science and Technology of the People's Republic of China National Key R&D Program of China(2017YFC1200605).
文摘In a tritrophic context of plant-insect-entomopathogen,plants play important roles in modulating the interaction of insects and their pathogenic viruses.Currently,the influence of plants on the transmission of insect viruses has been mainly studied on baculoviruses and some RNA viruses,whereas the impact of plants on other insect viruses is largely unknown.Here,we identified a new densovirus infecting the green peach aphid Myzus persicae and tested whether and how host plants influence the transmission of the aphid densovirus.The complete single-stranded DNA genome of the virus,M.persicae densovirus 2,is 5727 nt and contains inverted terminal repeats.Transcription and phylogenetic analysis indicated that the virus was distinct from other a few identified aphid densoviruses.The virus abundance was detected highly in the intestinal tract of aphids,compared with the lower level of it in other tissues including head,embryo,and epidermis.Cabbage and pepper plants had no obvious effect on the vertical transmission and saliva-mediated horizontal transmission of the virus.However,the honeydew-mediated horizontal transmission among aphids highly depended on host plants(65%on cabbages versus 17%on peppers).Although the virus concentration in the honeydew produced by aphids between 2 plants was similar,the honeydew production of the infected aphids reared on peppers was dramatically reduced.Taken together,our results provide evidence that plants influence the horizontal transmission of a new densovirus in an aphid population by modulating honeydew secretion of aphids,suggesting plants may manipulate the spread of an aphid-pathogenic densovirus in nature.
文摘Background Dengue virus(DENV)is a major public health threat,with Aedes albopictus being the confrmed vector responsible for dengue epidemics in Guangzhou,China.Mosquito densoviruses(MDVs)are pathogenic mosquitospecifc viruses,and a novel MDV was previously isolated from Ae.albopictus in Guangzhou.This study aims to determine the prevalence of MDVs in wild Ae.albopictus populations and investigate their potential interactions with DENV and impact on vector susceptibility for DENV.Methods The prevalence of MDV in wild mosquitoes in China was investigated using open access sequencing data and PCR detection in Ae.albopictus in Guangzhou.The viral infection rate and titers in MDV-persistent C6/36 cells were evaluated at 12,24,48,72,96,and 120 h post infection(hpi)by indirect immunofuorescence assay(IFA)and real time quantitative PCR(RT-qPCR).The midgut infection rate(MIR),dissemination rate(DR),and salivary gland infection rate(SGIR)in various tissues of MDV-infected mosquitoes were detected and quantifed at 0,5,10,and 15 days post infection(dpi)by RT-PCR and RT-qPCR.The chi-square test evaluated dengue virus serotype 2(DENV-2)and Aedes aegypti densovirus(AaeDV)infection rates and related indices in mosquitoes,while Tukey’s LSD and t-tests compared viral titers in C6/36 cells and tissues over time.Results The results revealed a relatively wide distribution of MDVs in Aedes,Culex,and Anopheles mosquitoes in China and an over 68%positive rate.In vitro,signifcant reductions in DENV-2 titers in supernatant at 120 hpi,and an appar‑ent decrease in DENV-2-positive cells at 96 and 120 hpi were observed.In vivo,DENV-2 in the ovaries and salivary glands was frst detected at 10 dpi in both monoinfected and superinfected Ae.albopictus females,while MDV super‑infection with DENV-2 suppressed the salivary gland infection rate at 15 dpi.DENV-2 titer in the ovary and salivary glands of Ae.albopictus was reduced in superinfected mosquitoes at 15 dpi.Conclusions MDVs is widespread in natural mosquito populations,and replication of DENV-2 is suppressed in MDVinfected Ae.albopictus,thus reducing vector susceptibility to DENV-2.Our study supports the hypothesis that MDVs may contribute to reducing transmission of DENV and provides an alternative strategy for mosquito-transmitted disease control.
基金This work was supported by the National Natural Science Foundation of China(Grant No.10274106)NIH(USA)+2 种基金the Welch Foundationthe American Heart AssociationJMB was an HAMBP trainee supported by NIH(5T32GM08280).
文摘The three-dimensional structure of capsid of Aedes albopictus C6/36 densovirus was determined to 14- resolution by electron cryomicroscopy and computer reconstruction. The triangulation number of the capsid is 1. There are 12 holes in each triangular face and a spike on each 5-fold vertex. The validity of the capsid and nucleic acid densities in the reconstructions was discussed.
基金Supported by the National Natural Science Foundation of China (Grant No. 10274106 to Jingqiang Zhang)Welch Foundation (AU-1492 to Z. H. Zhou)Natural Science Foundation of Guangdong Province, China (05300232 to Lingpeng Cheng)
文摘Parvoviridae is a family of the smallest viruses known with a wide variety of hosts. The capsid structure of the Aedes albopictus C6/36 cell densovirus (C6/36 DNV) at 1.2-nm resolution was obtained by elec-tron cryomicroscopy (cryoEM) and three-dimensional (3D) image reconstruction. Structure compari-sons between the C6/36 DNV and other parvoviruses reveal that the degree of structural similarity be-tween C6/36 DNV and the human parvovirus B19 is higher than that between C6/36 DNV and other in-sect parvoviruses. The amino acid sequence comparisons of structural and non-structural proteins also reveal higher levels of similarity between C6/36 DNV and parvovirus B19 than those between C6/36 DNV and other parvoviruses. These findings indicate that C6/36 DNV is closely related to the human virus B19, and the former might evolve from the human species other than from other insect viruses.
文摘We have cloned the replicative form of the Periplaneta fuliginosa densonucleosis virus (PfDNV) genome and determined its complete sequence. The sequence has 5 454 nucleotides (nt), the genome consists of an internal unique sequence flanked by inverted terminal repeats (201 nt). The first 122 nt at the 5’end and the terminal 122 nt at the 3’end of both plus and minus strands can fold into a typical hairpin structure. The genome contains seven major open reading frames (ORFs). The plus strand has 4 ORFs occupying the 5’half of the plus strand, whereas the others span the 5’ half of the minus strand. Two potential promoters were found at map units (m.u.) 3 and 97. Computer analysis of sequence homologies with other parvoviruses suggests that the plus strand of Pf DNV encodes very likely the nonstructural proteins and the minus strand probably encodes the structural proteins.
