Seromolecular surveillance of rabbit haemorrhagic disease virus in Nigeria

Abstract

Following the first 2020 rabbit haemorrhagic disease virus (RHDV) outbreak in Nigeria which caused massive mortalities in several rabbitries, there was a need to know the spread and strains circulating in the affected states. Over 100 rabbitries still existing post-RHDV outbreak in Ogun and Kwara States were investigated. A commercial enzyme-linked immunosorbent assay kit was used to screen for RHDV immunoglobulin G in 192 rabbit sera, while RHDV VP60 gene was amplified in RNA extracted from these sera and tissues (liver and/or spleen harvested from 37 carcasses necrotized) by reverse transcription-polymerase chain reaction (RT-PCR). Sequences obtained from the amplicons were subjected to phylogenetic analysis. The results revealed a seroprevalence of 82.3% (158/192). RHDV VP60 gene was detected in 15/17 (88.2%) and 2/20 (10.0%) carcasses from Ogun and Kwara States, respectively, while none of the sera was positive. Sequences of the two positive amplicons selected (one from each states) shared 98.95% nucleotide identity and belonged to RHDV 2/GI.2 strain. Also, nBLAST of these sequences revealed 98.43–99.55% homology with the prototype Nigerian RHDV strain RHDV/NGR/ILN/001 (MT996357.1). Furthermore, these strains clustered with this prototype and a German RHDV strain (LR899166.1). Pathologic lesions affecting the respiratory, cardiovascular, renal, lymphatic, and digestive systems were observed in necropsied carcasses. This study indicated that RHDV 2/GI.2 strain was the cause of 2020 RHD outbreak in Nigeria. Thus, while continuous public sensitization about RHD especially among rabbit farmers in Nigeria is important, efforts aimed at design and implementation of RHD vaccination policy, preferably using indigenous seed, should be expedited.

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Tropical Animal Health and Production (2023) 55:327
https://doi.org/10.1007/s11250-023-03753-7
REGULAR ARTICLES
Seromolecular surveillance ofrabbit haemorrhagic disease virus
inNigeria
OluwafemiBabatundeDaodu1 · JosephOjonugwaShaibu2· EmmanuelAyopoAderounmu3·
TaiwoOluwoleJolaoso3· DanielOladimejiOluwayelu4· OlatundeBabatundeAkanbi5· IsaacDayoOlorunshola1·
JuliusOlaniyiAiyedun6· OladapoOyedejiOludairo6· RosemaryAjumaAudu2· OluwakemiChristianaDaodu7
Received: 12 September 2022 / Accepted: 12 September 2023 / Published online: 26 September 2023
© The Author(s), under exclusive licence to Springer Nature B.V. 2023
Abstract
Following the first 2020 rabbit haemorrhagic disease virus (RHDV) outbreak in Nigeria which caused massive mortalities in
several rabbitries, there was a need to know the spread and strains circulating in the affected states. Over 100 rabbitries still
existing post-RHDV outbreak in Ogun and Kwara States were investigated. A commercial enzyme-linked immunosorbent
assay kit was used to screen for RHDV immunoglobulin G in 192 rabbit sera, while RHDV VP60 gene was amplified in RNA
extracted from these sera and tissues (liver and/or spleen harvested from 37 carcasses necrotized) by reverse transcription-
polymerase chain reaction (RT-PCR). Sequences obtained from the amplicons were subjected to phylogenetic analysis. The
results revealed a seroprevalence of 82.3% (158/192). RHDV VP60 gene was detected in 15/17 (88.2%) and 2/20 (10.0%)
carcasses from Ogun and Kwara States, respectively, while none of the sera was positive. Sequences of the two positive
amplicons selected (one from each states) shared 98.95% nucleotide identity and belonged to RHDV 2/GI.2 strain. Also,
nBLAST of these sequences revealed 98.43–99.55% homology with the prototype Nigerian RHDV strain RHDV/NGR/
ILN/001 (MT996357.1). Furthermore, these strains clustered with this prototype and a German RHDV strain (LR899166.1).
Pathologic lesions affecting the respiratory, cardiovascular, renal, lymphatic, and digestive systems were observed in necrop-
sied carcasses. This study indicated that RHDV 2/GI.2 strain was the cause of 2020 RHD outbreak in Nigeria. Thus, while
continuous public sensitization about RHD especially among rabbit farmers in Nigeria is important, efforts aimed at design
and implementation of RHD vaccination policy, preferably using indigenous seed, should be expedited.
Keywords Genetic sequence· Immunoglobulin G· Nigeria· Rabbit haemorrhagic disease virus· Pathological lesions·
RT-PCR
* Oluwafemi Babatunde Daodu
daodu.ob@unilorin.edu.ng
1 Department ofVeterinary Microbiology, Faculty
ofVeterinary Medicine, University ofIlorin, Ilorin,
KwaraState, Nigeria
2 Center forHuman Virology andGenomics, Nigerian Institute
forMedical Research, Yaba, LagosState, Nigeria
3 Ogun State Ministry ofAgriculture andRural Development,
Ogun State, Abeokuta, Nigeria
4 Department ofVeterinary Microbiology, Faculty
ofVeterinary Medicine, University ofIbadan, Ibadan,
OyoState, Nigeria
5 Department ofVeterinary Pathology, Faculty ofVeterinary
Medicine, University ofIlorin, Ilorin, KwaraState, Nigeria
6 Department ofVeterinary Public Health andPreventive
Medicine, Faculty ofVeterinary Medicine, University
ofIlorin, Ilorin, KwaraState, Nigeria
7 Department ofWildlife andEcotourism, Faculty
ofAgriculture andForestry, University ofIbadan, Ibadan,
OyoState, Nigeria
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