Comparative analysis of serological methods in diagnostics of infection caused by West Nile virus

Virus Zapadnog Nila (West Nile virus-WNV) je izolovan 1937. godine u West Nile distrihtu u Ugandi, po čemu je i dobio ime. Pripada familiji Flaviviridae i rodu Flavivirus. Prenosi se putem insekata-komaraca pa se svrstava u grupu Arbovirusa, a ptice predstavljaju prave domaćine i rezervoare virusa u prirodi. Čovek i sisari su slučajni domaćini koji obolevaju sa kliničkom slikom neuroinvazivnog oboljenja. Brojne epidemije koje je izazvao su bile praćene velikim brojem obolelih ljudi i životinja i materijalnim štetama. Serološka laboratorijska dijagnostika infekcije WNV je složena zbog unakrsnih reakcija sa drugim virusima iz iste familije (Japanski encefalitis, krpeljski encefalitis, Usutu i dr.), ali i odabira dijagnostičkog metoda koji će dati najoptimalnije rezultate. Cilj istraživanja je bio da se pripreme „in house“ testovi (AGID, IFA i ELISA) za serološku dijagnostiku WNV i da se uporede dobijeni rezultati „in house“ testova sa rezultatima dobijenih primenom komercijalno dostupnih testova u cilјu određivanja osetlјivosti i specifičnosti upotreblјenih testova radi utvrđivanja koji od primenjenih testova su najpogodniji za otkrivanje infekcije WNV. Primenom pomenutih testova utvrđena je seroprevalencija u populacijama ispitivanih vrsta (konji, lјudi, psi) na odabranim lokalitetima Republike Srbije, što omogućava mapiranje ugroženih područja i definisanje mera kontrole i suzbijanja infekcije. Ispitano je ukupno 153 krvna seruma ljudi, 303 krvna seruma konja i 184 krvna seruma pasa. Uzorci su prikupljeni u periodu od 2011.-2013. godine na ukupno 15 različitih lokaliteta- regiona Republike Srbije. Ustanovljena seroprevalencija je varirala u odnosu na lokalitet sa većom vrednošću u regionima u slivu Save i Dunava. Pripremljena su tri „in house“ testa (AGID, IFA i ELISA), a rezultati testova su upoređeni sa rezultatima komercijalno dostupnih testova. Statističkim poređenjem primenom McNemarove metode nisu utvrđene statistički značajne razlike između „in house“ IFA testa i komercijalno dostupnog testa na uzorcima poreklom od ljudi i konja...West Nile virus (WNV) was discovered in West Nile district of Uganda in 1937., and named after place of discovery. It is classified in fam. Flaviviridae and genus Flavivirus. WNV is transmitted via insects-mosquitos and it is a member of Arbovirus group. Birds are true hosts and reservoirs of virus in nature. Humans and other mammals are accidental hosts showing clinical signs of neuroinvasive disease. Numerous epidemics caused by WNV were followed by large number of affected people and animals and significant economical loses. Serological laboratory diagnostics is difficult due to cross reactions with other viruses from the same family (Japanese encephalitis virus, tick born encephalitis virus, Usutu etc), and right choice of diagnostic method which would give the most satisfactory results. The goal of research was to prepare „in house“ tests (AGID, IFA and ELISA) for serological diagnostics of WNV, to compare the obtained results of „in house“ and commercially available test in order to determinate sensitivity and specificity of „in house“ tests and the most satisfactory tests in diagnostic of WNV infection. The seroprevalence was determined by use of prepared and available test in populations of horse, dog and human in investigated chosen regions of the Republic of Serbia, which enabled the mapping of endangered areas and definition of control and eradication measures. Total of 153 human blood sera, 303 horse sera and 184 dog sera were collected in period from 2011. to 2013. in 15 different localities of the Republic of Serbia. Determined seroprevalence varies in localities with higher value in localities near Sava and Danube river. Three „in house“ test were made (AGID, IFA and ELISA) and the results were compared to results of commercially available test by use of McNemar test. The statistically significant differences were not established between „in house“ and commercial IFA test in horse and human samples. The use of IFA tests was not possible in dogs due to unspecific reaction..