Detekcija neurovirulentnih sojeva konjskog herpesvirusa 1

Abstract

Konjski herpesvirus 1 (EHV-1) kao jedan od najznačajnijih uzročnika infekcija konja koji nanosi velike ekonomske štete dovodeći do pojave rinopneumonitisa, pobačaja i neuroloških poremećaja. EHV-1 opstaje u populaciji prijemčivih domaćina zahvaljujući ciklusima latencije i reaktivacije virusa šireći se direktnim ili indirektnim kontaktom. Mutacija na nivou jednog nukleotida u okviru ORF30 gena koji kodira sintezu virusne DNK polimeraze uslovljava neurovirulentni potencijal sojeva EHV-1. Primenom metoda izolacije virusa i PCR ispitano je 140 uzoraka tkiva i nosnih briseva klinički zdravih nevakcinisanih konja kao i sojevi EHV-1 izolovani iz pobačenih fetusa. Ispitivana je rasprostranjenost i virulencija sojeva EHV-1 kao i klinički značaj dobijenih rezultata. Detektovano je 115 pozitivnih uzoraka pri čemu je utvrđeno da 82% poseduje neurovirulentni genetski marker. Virulencija EHV-1 ne predstavlja presudni faktor za razvoj kliničkih simptoma oboljenja kod inficiranih konja. Neurovirulentni sojevi EHV-1 cirkulišu u populaciji klinički zdravih konja, međutim imaju značaj u slučajevima pobačaja gravidnih kobila. Pored toga, utvrđena je važna uloga nervnog tkiva za ostvarivanje latencije i reaktivacije EHV-1 kod klinički zdravih konja prethodno izloženih stresu. Naši rezultati ukazuju na značaj asimptomatski inficiranih konja koji izlučuju EHV-1 i mogu predstavljati izvor infekcije za imunološki neadaptirane jedinke što se mora uzimati u obzir prilikom mešanja konja iz različitih populacija.

Equine herpesvirus 1 (EHV-1) is one of the most important equine pathogens and causes rhinopneumonitis, abortion, and neurological disorders, leading to major economic losses. EHV-1 is maintained through latency and reactivation cycles, and spreads among horses by direct or indirect contact. The single nucleotide polymorphism within the ORF30 gene encoding the viral DNA polymerase conditions the neurovirulent potential of EHV-1 strains. A total of 140 tissue and nasal swab samples from clinically healthy unvaccinated horses, as well as EHV-1 strains isolated from aborted fetuses, were examined using virus isolation and PCR. The distribution and virulence of EHV-1 strains along with the clinical implications of the obtained results were analyzed. Overall, 115 positive samples were detected, with 82% containing the neurovirulent marker. EHV-1 virulence is not crucial for clinical symptom development in infected horses. Neurovirulent EHV-1 strains circulate among clinically healthy horses, however, they are also important in cases of abortion. Additionally, neural tissue has a major role in EHV-1 latency and reactivation in clinically healthy horses exposed to stress. Our results indicate that asymptomatically infected horses shed EHV-1 and may represent an infection source for immunologically unadapted individuals, which must be taken into account when mixing different populations of horses.