Vaccination with Rift Valley fever virus live attenuated vaccine strain Smithburn caused meningoencephalitis in alpacas.
J Vet Diagn Invest
; 33(4): 777-781, 2021 Jul.
Article
in En
| MEDLINE
| ID: mdl-34041966
ABSTRACT
Rift Valley fever (RVF) is a zoonotic, viral, mosquito-borne disease that causes considerable morbidity and mortality in humans and livestock in Africa and the Arabian Peninsula. In June 2018, 4 alpaca inoculated subcutaneously with live attenuated RVF virus (RVFV) Smithburn strain exhibited pyrexia, aberrant vocalization, anorexia, neurologic signs, and respiratory distress. One animal died the evening of inoculation, and 2 at ~20 d post-inoculation. Concern regarding potential vaccine strain reversion to wild-type RVFV or vaccine-induced disease prompted autopsy of the latter two. Macroscopically, both alpacas had severe pulmonary edema and congestion, myocardial hemorrhages, and cyanotic mucous membranes. Histologically, they had cerebral nonsuppurative encephalomyelitis with perivascular cuffing, multifocal neuronal necrosis, gliosis, and meningitis. Lesions were more severe in the 4-mo-old cria. RVFV antigen and RNA were present in neuronal cytoplasm, by immunohistochemistry and in situ hybridization (ISH) respectively, and cerebrum was also RVFV positive by RT-rtPCR. The virus clustered in lineage K (100% sequence identity), with close association to Smithburn sequences published previously (identity 99.1-100%). There was neither evidence of an aberrant immune-mediated reaction nor reassortment with wild-type virus. The evidence points to a pure infection with Smithburn vaccine strain as the cause of the animals' disease.
Key words
Full text:
1
Collection:
01-internacional
Database:
MEDLINE
Main subject:
Rift Valley fever virus
/
Camelids, New World
/
Vaccines, Attenuated
/
Viral Vaccines
/
Vaccination
/
Meningoencephalitis
Type of study:
Diagnostic_studies
Limits:
Animals
Country/Region as subject:
Africa
Language:
En
Journal:
J Vet Diagn Invest
Journal subject:
MEDICINA VETERINARIA
Year:
2021
Document type:
Article
Affiliation country:
South Africa