MicroRNAs (miRNAs) are key regulators of plant-pathogen interactions. Modulating miRNA function has emerged as a new strategy to produce virus resistance traits. However, the miRNAs involved in antiviral defence and the underlying mechanisms remain largely elusive. We previously demonstrated that sequestration by Argonaute (AGO) proteins plays an important role in regulating miRNA function in antiviral defence pathways. Here we reveal that cleavage-defective AGO18 complexes sequester microRNA528 (miR528) upon viral infection. We show that miR528 negatively regulates viral resistance in rice by cleaving L-ascorbate oxidase (AO) messenger RNA, thereby reducing AO-mediated accumulation of reactive oxygen species. Upon viral infection, miR528 becomes preferentially associated with AGO18, leading to elevated AO activity, higher basal reactive oxygen species accumulation and enhanced antiviral defence. Our findings reveal a mechanism in which antiviral defence is boosted through suppression of an miRNA that negatively regulates viral resistance. This mechanism could be manipulated to engineer virus-resistant crop plants.

BackgroundThe small brown planthopper (Laodelphax striatellus) is an important agricultural pest that not only damages rice plants by sap-sucking, but also acts as a vector that transmits rice stripe virus (RSV), which can cause even more serious yield loss. Despite being a model organism for studying entomology, population biology, plant protection, molecular interactions among plants, viruses and insects, only a few genomic sequences are available for this species. To investigate its transcriptome and determine the differences between viruliferous and naïve L. striatellus, we employed 454-FLX high-throughput pyrosequencing to generate EST databases of this insect.ResultsWe obtained 201,281 and 218,681 high-quality reads from viruliferous and naïve L. striatellus, respectively, with an average read length as 230 bp. These reads were assembled into contigs and two EST databases were generated. When all reads were combined, 16,885 contigs and 24,607 singletons (a total of 41,492 unigenes) were obtained, which represents a transcriptome of the insect. BlastX search against the NCBI-NR database revealed that only 6,873 (16.6%) of these unigenes have significant matches. Comparison of the distribution of GO classification among viruliferous, naïve, and combined EST databases indicated that these libraries are broadly representative of the L. striatellus transcriptomes. Functionally diverse transcripts from RSV, endosymbiotic bacteria Wolbachia and yeast-like symbiotes were identified, which reflects the possible lifestyles of these microbial symbionts that live in the cells of the host insect. Comparative genomic analysis revealed that L. striatellus encodes similar innate immunity regulatory systems as other insects, such as RNA interference, JAK/STAT and partial Imd cascades, which might be involved in defense against viral infection. In addition, we determined the differences in gene expression between vector and naïve samples, which generated a list of candidate genes that are potentially involved in the symbiosis of L. striatellus and RSV.ConclusionsTo our knowledge, the present study is the first description of a genomic project for L. striatellus. The identification of transcripts from RSV, Wolbachia, yeast-like symbiotes and genes abundantly expressed in viruliferous insect, provided a starting-point for investigating the molecular basis of symbiosis among these organisms.

-66, and -68). Detection of at least 50 IU of HPV16 or HPV18 DNA and of 500 genome equivalents (GE) of the other 14 HPV types (in samples with single and multiple HPV types) was considered proficient. Fifty-four laboratories worldwide submitted a total of 84 data sets. More than 21 HPV-genotyping assays were used. Commonly used methods were Linear Array, Lineblot, InnoLiPa, Clinical Array, type-specific real-time PCR, PCR-Luminex and microarray assays. The major oncogenic HPV types (HPV16 and -18) were detected in 89.7% (70/78) and 92.2% (71/77) of the data sets, respectively. HPV types 56, 59, and 68 were the least commonly detected types (in less than 80% of the data sets). Twenty-eight data sets reported multiple false-positive results and were considered nonproficient. In conclusion, we found that international proficiency studies, traceable to international standards, allow standardized quality assurance for different HPV-typing assays and enable the comparison of data generated from different laboratories worldwide.Human papillomavirus (HPV) infection has been established as the major cause of cervical cancer (2). Epidemiological studies have classified genital HPV types into high-and low-risk HPV types, reflecting their association with invasive cancer (19). The most important high-risk types, HPV16 and HPV18, account for about 70% of all invasive cervical cancers worldwide. The next most common HPV types on all continents are HPV31, -33, -35, -45, -52, and -58, found in approximately 20% of cervical cancers (19).An accurate and internationally comparable HPV DNA detection and typing methodology is an essential component in the evaluation of HPV vaccines and in effective implementation and monitoring of HPV vaccination programs. The genotyping assays used today differ in their performance with regard to type-specific detection rates (10). As the methodology for quality assurance and evaluation of assay performance is not standardized, comparisons between different studies that use different assays is particularly difficult (10).The World Health Organization (WHO) establishes international biological standard materials and reference reagents for substances of biological origin used in prophylaxis and in therapy or diagnosis of human diseases (http://www.who.int /biologicals/reference_preparations/en/). At the WHO meeting held in Geneva, Switzerland, from 15 to 17 August 2005, an expert group recommended the establishment of a global HPV laboratory network (HPV LabNet) to contribute to improving the quality of laboratory services for effective surveillance and HPV vaccination impact monitoring. Major activities within the HPV LabNet include the development of international standard reagents and standard operating procedures (SOPs) and the development of internationally comparable quality assurance methods (5, 26).International proficiency panels are already widely used for several microorganisms, including hepatitis A, B, and C viruses; herpes simplex virus (HSV); and human immunodeficiency virus (HIV) (15,...

C ervical cancer is the second most common type of cancer among women worldwide, with human papillomavirus (HPV) infection linked to more than 99% of cervical cancers (3, 37). The most important high-risk types, HPV type 16 (HPV-16) and HPV-18, account for about 70% of all invasive cervical cancers worldwide (27).An accurate and internationally comparable HPV DNA detection and genotyping methodology is an essential component both in the evaluation of HPV vaccines and in the effective implementation and monitoring of HPV vaccination programs. Genotyping assays used today differ in their analytical performance with regard to type-specific sensitivity and specificity (15). Several studies have compared different HPV typing assays using various clinical samples to assess their performance (7,17,24). However, in addition, evaluation of assay performance needs to be performed in a standardized manner, where different assay performances can be evaluated and results can be compared against a known and accepted standard over time (15).In 2005, the World Health Organization (WHO) initiated the establishment of the global HPV Laboratory Network (LabNet) with the objective to facilitate the development and implementation of HPV vaccines by improving and standardizing the quality of HPV laboratory services used for HPV surveillance and HPV vaccination impact monitoring. The main activities within the HPV LabNet include harmonization and standardization of laboratory procedures by the development of internationally comparable quality assurance methods, international standards, and reference reagents and standard operating procedures (SOPs) for vaccinology (8, 9, 38).Regularly issued global proficiency studies are essential for establishing comparable and reliable laboratory services. A number of international proficiency panels for quality assurance of laboratory testing are being conducted widely for a number of infectious agents. For example, the WHO measles and rubella laboratory networks have been distributing proficiency panels worldwide yearly since 2001, with the purpose to monitor the performance of laboratories and assay methodology over time (31). As there is no natural source of biological material that could be used to generate type-specific HPV international standards (ISs), recombinant HPV DNA plasmids were used to establish ISs of HPV-16 and HPV-18 DNA in 2008 with an assigned potency in international units (IU) (39). In 2008, the WHO HPV LabNet conducted a proficiency study based on HPV DNA plasmids containing the genomes from 14 oncogenic HPV types and 2 benign HPV types and open for participation to laboratories worldwide (6). That study demonstrated that it is possible to perform global proficiency studies with unitage traceable to ISs based on plasmid DNA and that such studies can provide an overview of the status of the HPV detection and typing methodology worldwide.

Highlights d Jasmonate (JA) signaling positively regulates rice antiviral defense d JA signaling and RNA silencing synergistically promote rice antiviral defense d JAMYB is the JA-responsive transcription factor that regulates AGO18 expression d Rice stripe virus coat protein (CP) triggers JA-AGO18mediated antiviral immune defense

No abstract

The global research and development of mRNA vaccines have been prodigious over the past decade, and the work in this field has been stimulated by the urgent need for rapid development of vaccines in response to an emergent disease such as the current COVID-19 pandemic. Nevertheless, there remain gaps in our understanding of the mechanism of action of mRNA vaccines, as well as their long-term performance in areas such as safety and efficacy. This paper reviews the technologies and processes used for developing mRNA prophylactic vaccines, the current status of vaccine development, and discusses the immune responses induced by mRNA vaccines. It also discusses important issues with regard to the evaluation of mRNA vaccines from regulatory perspectives. Setting global norms and standards for biologicals including vaccines to assure their quality, safety and efficacy has been a WHO mandate and a core function for more than 70 years. New initiatives are ongoing at WHO to arrive at a broad consensus to formulate international guidance on the manufacture and quality control, as well as nonclinical and clinical evaluation of mRNA vaccines, which is deemed necessary to facilitate international convergence of manufacturing and regulatory practices and provide support to National Regulatory Authorities in WHO member states.

No abstract