Lake Sinai virus is a diverse, globally distributed but not emerging multi-strain honeybee virus.

Domesticated honeybees and wild bees are some of the most important beneficial insects for human and environmental health, but infectious diseases pose a serious risk to these pollinators, particularly following the emergence of the ectoparasitic mite Varroa destructor as a viral vector. The acquisition of this novel viral vector from the Asian honeybee Apis ceranae has fundamentally changed viral epidemiology in its new host, the western honeybee A. mellifera. While the recently discovered Lake Sinai Viruses (LSV) have been associated with weak honeybee colonies, they have not been associated with vector-borne transmission. By combining a large-scale multi-year survey of LSV in Chinese A. mellifera and A. cerana honeybee colonies with globally available LSV-sequence data, we investigate the global epidemiology of this virus. We find that globally distributed LSV is a highly diverse multi-strain virus, which is predominantly associated with the western honeybee A. mellifera. In contrast to the vector-borne deformed wing virus, LSV is not an emerging disease. Instead, demographic reconstruction and strong global and local population structure indicates that it is a highly variable multi-strain virus in a stable association with its main host, the western honeybee. Prevalence patterns in China suggest a potential role for migratory beekeeping in the spread of this pathogen, demonstrating the potential for disease transmission with the man-made transport of beneficial insects.

Genomics and proteomics of Apis mellifera filamentous virus isolated from honeybees in China.

Apis mellifera filamentous virus (AmFV) is a large DNA virus that is endemic in honeybee colonies. The genome sequence of the AmFV Swiss isolate (AmFV CH-C05) has been reported, but so far very few molecular studies have been conducted on this virus. In this study, we isolated and purified AmFV (AmFV CN) from Chinese honeybee (Apis mellifera) colonies and elucidated its genomics and proteomics. Electron microscopy showed ovoid purified virions with dimensions of 300-500 â€‹× â€‹210-285 â€‹nm, wrapping a 3165 â€‹× â€‹40 â€‹nm filamentous nucleocapsid in three figure-eight loops. Unlike AmFV CH-C05, which was reported to have a circular genome, our data suggest that AmFV CN has a linear genome of approximately 493 â€‹kb. A total of 197 ORFs were identified, among which 36 putative genes including 18 baculoviral homologs were annotated. The overall nucleotide similarity between the CN and CH-C05 isolates was 96.9%. Several ORFs were newly annotated in AmFV CN, including homologs of per os infectivity factor 4 (PIF4) and a putative integrase. Phylogenomic analysis placed AmFVs on a separate branch within the newly proposed virus class Naldaviricetes. Proteomic analysis revealed 47 AmFV virion-associated proteins, of which 14 had over 50% sequence coverage, suggesting that they are likely to be main structural proteins. In addition, all six of the annotated PIFs (PIF-0-5) were identified by proteomics, suggesting that they may function as entry factors in AmFV infection. This study provides fundamental information regarding the molecular biology of AmFV.

Identification of Immune Response to Sacbrood Virus Infection in Apis cerana Under Natural Condition.

Chinese sacbrood virus (CSBV) is a serious threat to eastern honeybees (Apis cerana), especially larvae. However, the pathological mechanism of this deadly disease remains unclear. Here, we employed mRNA and small RNA (sRNA) transcriptome approach to investigate the microRNAs (miRNAs) and small interfering RNAs (siRNAs) expression changes of A. cerana larvae infected with CSBV under natural condition. We found that serine proteases involved in immune response were down-regulated, while the expression of siRNAs targeted to serine proteases were up-regulated. In addition, CSBV infection also affected the expression of larvae cuticle proteins such as larval cuticle proteins A1A and A3A, resulting in increased susceptibility to CSBV infection. Together, our results provide insights into sRNAs that they are likely to be involved in regulating honeybee immune response.

Occurrence and Molecular Phylogeny of Honey Bee Viruses in Vespids.

Since the discovery that honey bee viruses play a role in colony decline, researchers have made major breakthroughs in understanding viral pathology and infection processes in honey bees. Work on virus transmission patterns and virus vectors, such as the mite Varroa destructor, has prompted intense efforts to manage honey bee health. However, little is known about the occurrence of honey bee viruses in bee predators, such as vespids. In this study, we characterized the occurrence of 11 honey bee viruses in five vespid species and one wasp from four provinces in China and two vespid species from four locations in France. The results showed that all the species from China carried certain honey bee viruses, notably Apis mellifera filamentous virus (AmFV), Deformed wing virus (DWV), and Israeli acute paralysis virus (IAPV); furthermore, in some vespid colonies, more than three different viruses were identified. In France, DWV was the most common virus; Sacbrood virus (SBV) and Black queen cell virus (BQCV) were observed in one and two samples, respectively. Phylogenetic analyses of IAPV and BQCV sequences indicated that most of the IAPV sequences belonged to a single group, while the BQCV sequences belonged to several groups. Additionally, our study is the first to detect Lake Sinai virus (LSV) in a hornet from China. Our findings can guide further research into the origin and transmission of honey bee viruses in Vespidae, a taxon of ecological, and potentially epidemiological, relevance.

Prevalence and population genetics of the emerging honey bee pathogen DWV in Chinese apiculture.

Honey bees are agriculturally important, both as pollinators and by providing products such as honey. The sustainability of beekeeping is at risk through factors of global change such as habitat loss, as well as through the spread of infectious diseases. In China and other parts of Asia, beekeepers rely both on native Apis cerana and non-native Apis mellifera, putting bee populations at particular risk of disease emergence from multi-host pathogens. Indeed, two important honey bee parasites have emerged from East Asian honey bees, the mite Varroa destructor and the microsporidian Nosema ceranae. As V. destructor vectors viral bee diseases, we investigated whether another key bee pathogen, Deformed Wing Virus (DWV), may also have originated in East Asian honey bee populations. We use a large-scale survey of apiaries across China to investigate the prevalence and seasonality of DWV in managed A. mellifera and A. cerana colonies, showing that DWV-A prevalence was higher in A. mellifera, with a seasonal spike in prevalence in autumn and winter. Using phylogenetic and population genetic approaches, we show that while China and East Asian DWV isolates show comparatively high levels of genetic diversity, these bee populations are not a source for the current global DWV epidemic.

Discovery of Aphid Lethal Paralysis Virus in Vespa velutina and Apis cerana in China.

Honey bees are essential to the functioning of terrestrial ecosystems. However, despite no single factor being blamed for losses of honey bee colonies in Europe and the USA, viruses have been considered as a major driver. Moreover, a virus vector can enhance the titer and virulence of virus such as Varroa destructor can change the virulence of the deformed wing virus. Here, we report molecular evidence for aphid lethal paralysis virus (ALPV) infecting Vespa velutina, which is an important predator of honey bees, especially of Apis cerana. Viral replication and phylogenetic analysis indicated that ALPV can not only replicate in V. velutina and A. cerana, but ALPV from A. cerana (ALPV-Ac) was also significantly associated with that of V. velutina (ALPV-Vv), though distinct from those of Apis mellifera (ALPV-Am). The host state posterior probability displayed that V. velutina is the main viral reservoir between V. velutina and A. cerana. Our results show ALPV had expanded host diversity resulting in potential impacts on the health of pollinators, even on the pollination ecosystem. We suggest further studies should investigate potential risks and impacts on pollinator populations of hornets. These results should have an impact conservation efforts focused on sustaining native pollinator abundance and diversity, and therefore, the crucial ecosystem services that they provide.

Diverse Factors Affecting Efficiency of RNAi in Honey Bee Viruses.

Infection and transmission of honey bee viruses pose a serious threat to the pollination services of crops and wild plants, which plays a vital role in agricultural economy and ecology. RNA interference (RNAi) is an effective defense mechanism against commonly occurring viral infections of animals and plants. However, recent studies indicate that the effects of RNAi on the honey bee can induce additional impacts and might not always be effective in suppressing the virus. Moreover, the RNAi responses differed in relation to the developmental stage of the insect and the target tissue used, even though the same method of delivery was used. These results indicate that further analysis and field experiments should be performed to characterize the varying effectiveness of RNAi-based methods for treating honey bee viral infections. In this review, we provide an overview of the current knowledge and the recent progress in RNAi-based anti-viral treatments for honey bees, focusing in particular highlight the role of the dsRNA-delivery method used and its effect on RNAi efficiency and demonstrate the potential practical value of this tool for controlling the virus. We conclude studying the gene function and disease control of honey bee by RNAi technology requires a complex consideration from physiology, genetics to environment.

Complete sequences of the RNA 1 and RNA 2 segments of chronic bee paralysis virus strain CBPV-BJ detected in China.

Chronic bee paralysis virus (CBPV) is an important viral pathogen that affects adult bees. Although several CBPV strains have been reported, little information has been obtained from China. In this study, two major segments of the CBPV Chinese isolate CBPV-BJ, RNA 1 and RNA 2, were determined to be 3657 and 2267 nucleotides (nt) in length, respectively. RNA 1 and RNA 2 contained three and four open reading frames (ORFs), respectively, which agreed with known reference strains (EU122229 and EU122230). The RNA 1 had 98% nucleotide sequence identity to a known Chinese strain (KU950353), and RNA 2 had 97% nucleotide sequence identity to another Chinese strain (KU950354). Although the lengths of the RNA 1 and RNA 2 sequences were 17 nt and 38 nt shorter than those of the CBPV reference strains EU122229 and EU122230, respectively, the complete CBPV-BJ RNA 1 and RNA 2 sequences shared 91% and 92% identity with them. Phylogenetic analysis based on the sequences of the RNA-dependent RNA polymerase (RdRp) and putative structural proteins (pSPs) showed that CBPV-BJ was most closely related to the other two Chinese isolate (KU950353 and KU950354) and clustered with most Asian strains. These data provide new information that will lead to a better understanding of the diversity of the CBPV genome.

Infants' use of contextual cues in the generalization of effective actions from imitation.

We examined infants' ability to generalize effective actions in an imitation task. In Experiment 1, 15-month-olds imitated effective and ineffective actions on two similarly designed toys. They were then shown a third toy of the same design with both actions available. Children reliably touched and manipulated the effective action handle first and more persistently. In Experiment 2, however, 15-month-olds did not generalize the efficacy of the action when the test toy was different from the two demonstration toys. Experiment 3 replicated the findings of Experiment 2 but also showed that infants generalized efficacy when the demonstration toys differed from one another as well as from the test toy. Our findings are consistent with a computational model that uses certain rational pedagogical assumptions. Overall, the results suggest that 15-month-olds are sensitive to the sampling information they observe and use this information to guide whether to generalize efficacy information they learn from imitation.

Beyond the information given: infants' transfer of actions learned through imitation.

Five experiments were conducted to investigate infants' ability to transfer actions learned via imitation to new objects and to examine what components of the original context are critical to such transfer. Infants of 15 months observed an experimenter perform an action with one or two toys and then were offered a novel toy that was not demonstrated for them. In all experiments, infants performed target actions with the novel toy more frequently than infants who were offered the same toy but had seen no prior demonstrations. Infants exhibited transfer even when the specific part to be manipulated looked different across the toys, even when they had not performed the actions with the demonstration toys themselves, even when the actions produced no effects on the demonstrations, and even when the actions were demonstrated with only a single exemplar toy. Transfer was especially robust when infants not only observed but also practiced the target actions on the demonstration trials. Learning action affordances ("means") seems to be a central aspect of human imitation, and the propensity to apply these learned action affordances in new object contexts may be an important basis for technological innovation and invention.