Assembly of Recombinant Israeli Acute Paralysis virus capsids

The dicistrovirus Israeli Acute Paralysis Virus (IAPV) has been implicated in the worldwide decline of honey bees. Studies of IAPV and many other bee viruses in pure culture are restricted by available isolates and permissive cell culture. Here we show that coupling the IAPV major structural precursor protein ORF2 to its cognate 3C-like processing enzyme results in processing of the precursor to the individual structural proteins in a number of insect cell lines following expression by a recombinant baculovirus. The efficiency of expression is influenced by the level of IAPV 3C protein and moderation of its activity is required for optimal expression. The mature IAPV structural proteins assembled into empty capsids that migrated as particles on sucrose velocity gradients and showed typical dicistrovirus like morphology when examined by electron microscopy. Monoclonal antibodies raised to recombinant capsids were configured into a diagnostic test specific for the presence of IAPV. Recombinant capsids for each of the many bee viruses within the picornavirus family may provide virus specific reagents for the on-going investigation of the causes of honeybee loss.

Potential for virus transfer between the honey bees Apis mellifera and A. cerana

Viruses seem to play a key role in European honey bee, Apis mellifera health, and have a much broader host spectrum than previously thought. Few studies have investigated interspecific virus transfer within the genus Apis. The introduction of A. mellifera into Asia exposed endemic Apis species to the risk of obtaining new viruses or viral strains and vice versa. To investigate the potential for host shifts, virus prevalence and sequences were monitored over three years in single and mixed-species apiaries hosting introduced A. mellifera and endemic Apis cerana. Deformed wing virus (DWV), Israeli acute paralysis virus (IAPV), black queen cell virus (BQCV), and sacbrood virus (SBV) were found, but not KBV, VDV-1, ABPV, or CBPV. Virus infections and prevalence were generally lower in A. cerana compared to A. mellifera, and varied over the years. The sequence data provided evidence for interspecific transfer of IAPV, BQCV, and DWV, but SBV strains seem to be species specific. Prevalence and sequence results taken together indicate that interspecific transfers of viruses are rare, even if honey bees are kept in close proximity. We discuss the pattern observed in the context host specificity and resistance. Our understanding of the extent of these exchanges is limited by a lack of knowledge on the mechanisms of adaptation of viruses to different hosts.

Monitorización de los principales patógenos de las abejas para la detección de alertas y riesgos sanitarios

Las abejas, principalmente la especie Apis mellifera, desarrollan una función biológica muy importante puesto que se encargan de polinizar diversos cultivos agrícolas y la flora silvestre de todo el mundo. No obstante, existen numerosos factores que influyen en el estado sanitario de las colonias de abejas y presentan además un alto grado de interacciones entre ellos. Algunos de los potenciales riesgos para la apicultura española ya han sido identificados, como por ejemplo las dos especies de microsporidios, Nosema apis y N. ceranae, que actúan como parásitos intracelulares obligados o los ectoparásitos Varroa destructor, Acarapis woodi o Braula coeca; así como numerosos virus capaces de infectar a Apis melífera, de los cuales los principales son el virus de las alas deformadas (DWV), el virus de las realeras negras (BQCV), el virus Kashmir (KBV), el virus de la parálisis aguda (ABPV) y su variante israelí (IAPV). Otras enfermedades que afectan fundamentalmente a la cría de abejas son la loque americana y la loque europea, ambas de origen bacteriano (Paenibacillus larvae y Melissococcus plutonius respectivamente), así como la ascosferosis causada por el hongo Ascosphaera apis. Otro riesgo potencial para las abejas es la posible entrada de agentes exóticos como el coleóptero Aethina tumida o el ácaro Tropilaelaps clareae cuya presencia en Europa debe ser declarada según la OIE (2015). Recientemente se ha incluido a los neogregarinos y tripanosomátidos como posibles agentes patógenos. Actualmente, N. ceranae junto con V. destructor son los principales agentes patógenos que producen problemas sanitarios de las colonias de abejas en Europa. Además, se considera que los patógenos podrían jugar un papel primordial en el incremento de mortalidad de las abejas detectado en distintos países durante los últimos años...

Metagenomic detection of viral pathogens in Spanish honeybees: co-infection by Aphid Lethal Paralysis, Israel Acute Paralysis and Lake Sinai Viruses

The situation in Europe concerning honeybees has in recent years become increasingly aggravated with steady decline in populations and/or catastrophic winter losses. This has largely been attributed to the occurrence of a variety of known and "unknown", emerging novel diseases. Previous studies have demonstrated that colonies often can harbour more than one pathogen, making identification of etiological agents with classical methods difficult. By employing an unbiased metagenomic approach, which allows the detection of both unexpected and previously unknown infectious agents, the detection of three viruses, Aphid Lethal Paralysis Virus (ALPV), Israel Acute Paralysis Virus (IAPV), and Lake Sinai Virus (LSV), in honeybees from Spain is reported in this article. The existence of a subgroup of ALPV with the ability to infect bees was only recently reported and this is the first identification of such a strain in Europe. Similarly, LSV appear to be a still unclassified group of viruses with unclear impact on colony health and these viruses have not previously been identified outside of the United States. Furthermore, our study also reveals that these bees carried a plant virus, Turnip Ringspot Virus (TuRSV), potentially serving as important vector organisms. Taken together, these results demonstrate the new possibilities opened up by high-throughput sequencing and metagenomic analysis to study emerging new diseases in domestic and wild animal populations, including honeybees.