Nyugat-nílusi vírus fertőzésre adott immunválasz – irodalmi áttekintés – II. rész: Humorális immunválasz, diagnosztika és vakcinázás

Abstract

ÖSSZEFOGLALÁS Az előző összefoglalóban a szerzők részletekbe menően ismertették a nyugat-ní- lusi vírus fertőzésre adott veleszületett immunválasz, valamint az adaptív immun- reakció celluláris komponensének folyamatát, ill. ezek szerepét a kórokozó elleni védelemben, adott esetben az immunpatológiás folyamatok kialakulásában. A második rész, a szerezett immunválasz másik ágáról, a humorális immunreakció részleteiről, valamint ennek diagnosztikai és vakcinázási vonatkozásairól nyújt részletes áttekintést, amelyek ismerete a diagnózis felállítása mellett a kórokozó elleni hatékony védekezésben is elengedhetetlen. SUMMARY West Nile virus (WNV) belongs to the Orthoflavivirus genus within the Flaviviridae family. WNV causes significant number of equine and human neurological cases worldwide. As we discussed in our latest summary, the innate and cellular immune response play substantial role in the protection against the pathogen, however, an exacerbated immune response can lead to immunpathological processses. It is considered that lifelong, or at least long-term immune protection develops in survivors against reinfection. The level of neutralising antibodies is considered the best indicator of the protection against orthoflaviviruses. The envelop protein (E-protein) is the major target of virus neutralising antibodies (nAbs). There is a different magnitude of antigenic similarity between the E-proteins of orthoflavi- viruses. Therefore, during an immune response against an orthoflavivirus, not just virus-specific but other orthoflavivirus-specific antibodies are produced, as well. On the one hand, these antibodies can provide protection or enhance the seve- rity of the infection with a heterologous Orthoflavivirus. On the other hand, this phenomenon can make the diagnosis of West Nile virus infection quite difficult in countries with other co-circulating Orthoflaviviruses. Due to the short-term and low titer viraemia in humans and horses, the diagnosis of WNV infection relies on serological methods, however, as stated earlier the interpretation of these results can be difficult due to the cross-reactivity among Orthoflaviviruses. Currently, there are 3 available WNV vaccines for horses in the European Union. All these vaccines guarantee protection against the severe neurological form of the infection for 6-12 months. However, the vaccination protocol for foals and older horses might need to be reconsidered. The second part of our review provides a deep summary of the humoral immune response against WNV with a special focus on the diagnosis and the preventive countermeasures against the infection.