Know more

About cookies

What is a "cookie"?

A "cookie" is a piece of information, usually small and identified by a name, which may be sent to your browser by a website you are visiting. Your web browser will store it for a period of time, and send it back to the web server each time you log on again.

Different types of cookies are placed on the sites:

  • Cookies strictly necessary for the proper functioning of the site
  • Cookies deposited by third party sites to improve the interactivity of the site, to collect statistics

Learn more about cookies and how they work

The different types of cookies used on this site

Cookies strictly necessary for the site to function

These cookies allow the main services of the site to function optimally. You can technically block them using your browser settings but your experience on the site may be degraded.

Furthermore, you have the possibility of opposing the use of audience measurement tracers strictly necessary for the functioning and current administration of the website in the cookie management window accessible via the link located in the footer of the site.

Technical cookies

Name of the cookie


Shelf life

CAS and PHP session cookies

Login credentials, session security



Saving your cookie consent choices

12 months

Audience measurement cookies (AT Internet)

Name of the cookie


Shelf life


Trace the visitor's route in order to establish visit statistics.

13 months


Store the anonymous ID of the visitor who starts the first time he visits the site

13 months


Identify the numbers (unique identifiers of a site) seen by the visitor and store the visitor's identifiers.

13 months

About the AT Internet audience measurement tool :

AT Internet's audience measurement tool Analytics is deployed on this site in order to obtain information on visitors' navigation and to improve its use.

The French data protection authority (CNIL) has granted an exemption to AT Internet's Web Analytics cookie. This tool is thus exempt from the collection of the Internet user's consent with regard to the deposit of analytics cookies. However, you can refuse the deposit of these cookies via the cookie management panel.

Good to know:

  • The data collected are not cross-checked with other processing operations
  • The deposited cookie is only used to produce anonymous statistics
  • The cookie does not allow the user's navigation on other sites to be tracked.

Third party cookies to improve the interactivity of the site

This site relies on certain services provided by third parties which allow :

  • to offer interactive content;
  • improve usability and facilitate the sharing of content on social networks;
  • view videos and animated presentations directly on our website;
  • protect form entries from robots;
  • monitor the performance of the site.

These third parties will collect and use your browsing data for their own purposes.

How to accept or reject cookies

When you start browsing an eZpublish site, the appearance of the "cookies" banner allows you to accept or refuse all the cookies we use. This banner will be displayed as long as you have not made a choice, even if you are browsing on another page of the site.

You can change your choices at any time by clicking on the "Cookie Management" link.

You can manage these cookies in your browser. Here are the procedures to follow: Firefox; Chrome; Explorer; Safari; Opera

For more information about the cookies we use, you can contact INRAE's Data Protection Officer by email at or by post at :


24, chemin de Borde Rouge -Auzeville - CS52627 31326 Castanet Tolosan cedex - France

Last update: May 2021


Home page

Research axis 1. Mechanisms involved in the production of PDV particles in the parasitoid

We are interested in better understanding the steps in viral replication leading to the production of particles specifically in calyx cells during the pupal and adult stages of the female parasitoid....

A first step was to characterize the genomic architecture of the endogenous viral sequences in H. didymator. The H. didymator genome was sequenced, showing that the viral regions were scattered throughout the wasp genome (Legeai et al, 2020). We were able to identify 60 proviral loci in the H. didymator genome, distributed among 32 scaffolds and separated by large portions of wasp's sequences. They correspond either to regions carrying genes from the viral ancestor involved in particle production, or 'replication genes', or to sequences serving as templates for circular DNA molecules, or 'segments', which are then incorporated into the particles and transferred during parasitism (Figure 2).

Figure 2_EN

Figure 2. Organization of polydnavirus sequences integrated into the parasitoid wasp genome. These sequences correspond either to segments (right) or to clusters of replication genes (left). The replication genes originate from the ancestor virus and are involved in the production of the virus particles. They are specifically expressed in the calyx cells of the pupa and adult. These genes are not encapsidated. In contrast, the segments are excised, circularized and then incorporated into the virus particles. They carry a set of genes that will be expressed in the tissues of the parasitized caterpillar. Their products are responsible for the alterations in the caterpillar's physiology necessary for the development of the parasitoid. Figure taken from the team's publication DOI: 10.1684/vir.2020.0835.

We now seek to decipher the function of the viral genes maintained in the wasp genome during evolution. A total of 54 genes potentially belonging to the ichnoviral machinery have been identified in the H. didymator genome (divided into 5 clusters and 1 isolated gene). With few exceptions, none of these genes shows similarity with known genes, and their actual function in viral particle formation remains to be demonstrated. To understand their role, we use RNA interference technology to inhibit their expression in vivo. The consequences of the knockdown on HdIV replication are then studied by combining electron microscopy and different "omics" and functional approaches.

A first study was carried out for six candidate genes, chosen because they are highly expressed in pupal calyxes and because they encode proteins identified during the proteomic analysis of purified virus particles (Lorenzi et al, 2019). This first-ever functional analysis of virus-derived particle production in an ichneumonid wasp showed that the genes studied were required for viral particle morphogenesis and cell trafficking, and that their functions are those expected of classical viral genes (Figure 3).

Figure 3

Figure 3. Schematic representation of the morphogenesis of ichnovirus virions. Ichnoviruses have an atypical morphogenesis, allowing calyx cells to produce particles throughout the life of the female parasitoid. Enveloped virions are assembled in the nucleus of calyx cells, bud through the nuclear envelope, and migrate towards the plasma membrane where they are secreted into the lumen of the oviduct, acquiring a second envelope. By inhibiting the expression of candidate genes by RNA interference, we were able to identify a gene (IVp12-1) involved in the formation of the virogenic stroma, two genes (U23 and IVSP4-1) involved in the assembly of nucleocapsids, two genes (U22 and IVSP3-1) involved in the exit of virions from the nucleus and a gene (IVp53-2) involved in the exit of virions from the cell. Figure taken from the team's publication DOI: 10.1371/journal.ppat.1008210.