Monitoring prevalencije divljih i cijepnih sojeva virusa Marekove bolesti pretragom pera i prašine qPCR postupkom na farmama kokoši nesilica

master's thesis

• Title (english): Monitoring the Prevalence of Wild and Vaccine Strains of Marek's Disease Virus by qPCR Testing of Feathers and Dust on Layer Farms
• Author: Helena Leskovar
• Mentor: Željko Gottstein (mentor)
• Committee member: Liča Lozica (predsjednik povjerenstva)
• Committee member: Maja Lukač (član povjerenstva)
• Committee member: Željko Gottstein (član povjerenstva)
• Granter: University of Zagreb; Faculty of Veterinary Medicine; Zagreb
• Defense date and country: 2024-07-08, Croatia
• Scientific / art field, discipline and subdiscipline: BIOMEDICINE AND HEALTHCARE; Veterinary Medicine; Veterinary Public Health and Food Safety

Abstract

Onkogeni virus iz porodice Herpesviridae uzročnik je Marekove bolesti, koja je karakterizirana
nastankom limfoidnih neoplastičnih promjena, imunosupresijom i prolaznom paralizom kokoši.
Marekova bolest ima značajan ekonomski utjecaj zbog visokog mortaliteta i morbiditeta, iako ne
pokazuje zoonotski potencijal. Međutim, visoki gubici, posebice zbog organoleptičkih promjena,
predstavljaju veliki problem u peradarskoj industriji. Virus Marekove bolesti je ubikvitaran i širi se
horizontalnim putem. Zbog sve učestalijeg povećanja virulencije VMB-i potrebna je učinkovita
strategija za kontrolu. U svrhu kontrole koristi se imunoprofilaksa, pri čemu je zlatni standard
cijepljenje CVI988 sojem. Ovo cjepivo pokazuje zaštitu protiv vrlo virulentnih sojeva i najčešće se
primjenjuje kod jednodnevnih pilića. Sva cjepiva mogu štititi od mortaliteta, kliničkih znakova i
učestalosti pojavljivanja lezija, ali nijedno ne pruža potpunu zaštitu od infekcije, replikacije i
izlučivanja divljeg virusa. Za bolje razumijevanje mehanizama cjepne zaštite korisno je pratiti
cjepne i divlje sojeve VMB-a. U tu svrhu moguće je koristi qPCR test na uzorcima perja i prašine.
U ovom radu istraživana je prisutnost cjepnih i divljih sojeva VMB-i na uzorcima perja i prašine s
dvije farme, ukupno iz sedam jata. Cjepni soj CVI988 bio je u značajno višem postotku dokazan u
jatima pilića dobi tri tjedna no u starijih jata, gdje je njihov dokaz izostao. Divlji soj VMB-a bio je
prisutan u većem postotku u jatima na početku proizvodnje i srednje dobi, dok kod pilića i starijih
jata nije dokazano njegovo prisustvo. Izuzetak je bilo starije jato K3, u kojem je zabilježena veća
učestalost cjepnog soja. Rezultati ukazuju na važnost praćenja sojeva VMB-a s ciljem praćenja
provedene imunoprofilakse te širenja i kontaminacije okoliša divljim sojevima.

Abstract (english)

The oncogenic virus from the Herpesviridae family is the causative agent of Marek's disease, which
is characterized by the formation of lymphoid neoplastic changes, immunosuppression and transient
paralysis in chickens. Marek's disease has a significant economic impact due to high mortality and
morbidity, although it does not exhibit zoonotic potential. However, high losses, due to organoleptic
changes, represent a major problem in the poultry industry. The Marek's disease virus is ubiquitous
and spreads horizontally. Due to the increasing virulence of MDV, an effective strategy for control
is needed. For control, immunoprophylaxis is used, with the vaccination using CVI988 strain as the
golden standard. This vaccine provides protection against very virulent strains and is most
commonly administered to day-old chicks. All vaccines could protect against mortality, clinical
signs, and the frequency of lesion occurrence, but none provide complete protection from infection,
replication, and shedding of the wild virus. For a better understanding of the mechanisms of vaccine
protection, it is useful to monitor vaccine and wild strains of MDV. For this purpose, qPCR testing
could be used on feather and dust samples. This study investigated the presence of vaccine and wild
strains of MDV in feather and dust samples from two farms, on seven flocks in total. The CVI988
vaccine strain was in significantly higher percentage detected in chicken flocks up to three weeks,
compared to older flocks, in which detection was absent. The wild MDV strain was present in a
higher percentage in flocks at the start of production and of intermediate age, while it was not
detected in chicks and older flocks. The exception was flock K3, where a higher prevalence of the
vaccine strain was recorded. Results emphasise the importance of MDV strain monitoring with the
aim of monitoring immunoprotection and spread and environmental contamination with wild
strains.

• Keywords: Marekova bolest; cijepljenje; qPCR; monitoring; cijepni soj; divlji soj
• Keywords (english): Marek's disease; vaccination; qPCR; monitoring; vaccine strain; wild strain
• Language: croatian
• URN:NBN: urn:nbn:hr:178:548159
• Study programme: Title: Veterinary Medicine; Study programme type: university; Study level: integrated undergraduate and graduate; Academic / professional title: doktor/doktorica veterinarske medicine (doktor/doktorica veterinarske medicine)
• Type of resource: Text
• File origin: Born digital
• Access conditions: Embargoed access; Embargo expiration date: 2025-02-15
• Created on: 2024-07-15 12:39:40