F-actin dynamics in midgut cells enables virus persistence in vector insects

An insect symbiotic virus promotes the transmission of a phytoarbovirus via inhibiting E3 ubiquitin ligase Sina

Co-infection with symbiotic viruses and arboviruses with synergistic effects in insect vectors are common in nature, but the underlying mechanism remains elusive. Here, we identify a novel symbiotic virus, leafhopper Recilia dorsalis bunyavirus (RdBV), which enhances the transmission efficiency of cytorhabdovirus rice stripe mosaic virus (RSMV, a plant rhabdovirus) in field. RSMV infection activates the expression of R. dorsalis E3 ubiquitin ligase Seven in absentia (RdSina), while RdBV infection suppresses its expression. We show that RdSina directly targets and mediates the degradation of RSMV phosphoprotein (P), thereby attenuating the formation of P-induced viroplasm that are crucial for viral replication. RdSina interacts with nonstructural protein NSs2 of RdBV but does not mediate its ubiquitination. However, NSs2 competes with RSMV P for binding to RdSina, thus neutralizing RdSina's ability in mediating P degradation. Furthermore, we find that the MYC transcription factor binds to the promoter sequences of RdSina, activating its transcription. However, NSs2 also directly binds to the same promoter sequences of RdSina and competitively suppresses MYC-activated RdSina transcription. Together, NSs2 obstructs the function of RdSina in mediating P degradation, ultimately promoting RSMV propagation in co-infected vectors. These findings elucidate how insect symbiotic viruses negatively regulate E3 ubiquitin ligases to benefit arbovirus transmission by co-infected insect vectors, which potentially is a common phenomenon in nature.

Mastrevirus Transmission by the Insect Vectors, Leafhoppers

Mastreviruses are important pathogens on many crops and they are transmitted in a persistent manner by leafhoppers. For experimental studies on mastreviruses, transmission with leafhoppers remains as an important method for virus inoculation. Here, we describe a protocol for setting up a culture of the leafhopper vector Psammotettix alienus and efficient leafhopper-mediated transmission of wheat dwarf virus.

Spatial differentiation characteristics of the Hemiptera insects in China

The Hemiptera insects are the largest incomplete metamorphosis insect group in Insecta and play a vital role in ecosystems and biodiversity. Previous studies on the spatial distribution of Hemiptera insects mainly focused on a specific region and insect, this study explored the spatial distribution characteristics of Hemiptera insects in China (national scale), and further clarified the dominant factors affecting their spatial distribution. We used spatial autocorrelation analysis, hot spot analysis, and standard ellipse to investigate the spatial distribution characteristics of Hemiptera insects in China. Furthermore, we used geographic detectors to identify the main factors affecting their spatial distribution under China's six agricultural natural divisions and explore the influencing mechanism of dominant factors. The results show that: (i) The spatial differentiation characteristics of Hemiptera insects in China are significant, and their distribution has obvious spatial agglomeration. The Hu Huanyong Line is an important dividing line for the spatial distribution of Hemiptera insects in China. From the city scale, the HH type (high-high cluster) is mainly distributed on both sides of the Hu Huanyong Line. (ii) The hot spots of Hemiptera insects are mainly distributed in southwest China, along the Qinling Mountains, the western side of the Wuyi Mountains, the Yinshan Mountains, the Liupanshan Mountains, the Xuefeng Mountains, the Nanling Mountains, and other mountainous areas. (iii) Under agricultural natural divisions, the influence of natural environmental factors on the spatial distribution of Hemiptera insects is obviously different. Temperature and precipitation are the dominant factors. Natural factors and socio-economic factors have formed a positive reinforcement interaction mode on the spatial distribution of Hemiptera insects. These can provide the decision-making basis for biodiversity conservation and efficient pest control.

Complex interactions among insect viruses-insect vector-arboviruses

Insects are the host or vector of diverse viruses including those that infect vertebrates, plants, and fungi. Insect viruses reside inside their insect hosts and are vertically transmitted from parent to offspring. The insect virus-host relationship is intricate, as these viruses can impact various aspects of insect biology, such as development, reproduction, sex ratios, and immunity. Arthropod-borne viruses (arboviruses) that cause substantial global health or agricultural problems can also be vertically transmitted to insect vector progeny. Multiple infections with insect viruses and arboviruses are common in nature. Such coinfections involve complex interactions, including synergism, dependence, and antagonism. Recent studies have shed light on the influence of insect viruses on the competence of insect vectors for arboviruses. In this review, we focus on the biological effects of insect viruses on the transmission of arboviruses by insects. We also discuss the potential mechanisms by which insect viruses affect the ability of hosts to transmit arboviruses, as well as potential strategies for disease control through manipulation of insect viruses. Analyses of the interactions among insect vectors, insect viruses and arboviruses will provide new opportunities for development of innovative strategies to control arbovirus transmission.

Hsp90 could promote BmNPV proliferation by interacting with Actin-4 and enhance its expression

As a highly infectious pathogen, Bombyx mori nuclear polyhedrosis virus (BmNPV) has a high lethality rate in silkworm. Our previous study have confirmed that Hsp90 plays a positive role in BmNPV proliferation and Hsp90 inhibitor, geldanamycin (GA) can decrease the replication of BmNPV in vitro. However, its molecular mechanism is not fully understood. In the present study, first, we found that GA could inhibit the proliferation of BmNPV in a dose-dependent manner and delay the pathogenesis of BmNPV in vivo possibly by altering the transcript level of genes associated with cell apoptosis and immune pathways. Furthermore, by immunoprecipitation (IP) and mass spectrometry analysis, we identified a series of proteins potentially interacting with Hsp90 including two BmNPV encoded proteins. Subsequently, by Co-IP we confirmed the interaction between BmActin-4 and BmHsp90. Knocking down Bmhsp90 by small interfering RNA inhibited the protein expression level of BmActin-4. Over-expression of Bmactin-4 promoted the replication of BmNPV whereas knockdown of Bmactin-4 suppressed BmNPV replication. In addition, decrease of the transcript level of Bmhsp90 in Bmactin-4 knocking down BmN cells was also detected. Taken together, BmHsp90 can interact with BmActin-4 and promote its expression, thereby promoting BmNPV proliferation. Our findings may enrich the molecular mechanism of Hsp90 for promoting virus proliferation and provide new clues to elucidate the interact mechanism between silkworm and virus.