Long-term RNA persistence of porcine rubulavirus (PorPV-LPMV) after an outbreak of a natural infection: the detection of viral mRNA in sentinel pigs suggests viral transmission.
The persistence of porcine rubulavirus (PorPV-LPMV) in five pigs that had survived an outbreak of a natural infection was determined. After the resolution of the outbreak, each animal was housed in an isolation pen together with one sentinel pig. Approximately every 2 months thereafter one group of animals was euthanized and tissue samples taken for virological and serological analysis. Infectious virus was not isolated from any samples; antibodies to PorPV-LPMV were detected in convalescent pigs by virus neutralisation test and blocking ELISA but not in sentinel pigs. PorPV-LPMV mRNA of the nucleoprotein (NP) and phosphoprotein (P) genes was detected by a nested polymerase chain reaction (nPCR) in samples of trigeminal and optic nerves, cervical spinal cord, tonsils, salivary gland, lung and pancreas from convalescent pigs. mRNA was also detected in the midbrain, corpus callosum, or olfactory bulb in four out of five pigs by nRT-PCR, this result was confirmed by the sequencing of a 260bp PCR product of P gene region. The highest average viral copies/μg of total RNA occurred in the olfactory bulb and pancreas tissues of convalescent pigs and midbrain, tonsil and pancreas of sentinel pigs housed with the convalescent pigs. Satellitosis and gliosis of the midbrain, olfactory bulb, corpus callosum, medulla oblongata or choroid plexus were microscopically observed in four convalescent pigs. The control pig remained negative in all tests. The results indicate that PorPV-LPMV mRNA persists and induces a durable humoral immune response in pigs that have recovered from a natural infection. After a possible reactivation of the virus, it was transmitted to sentinel pigs in contact with the convalescent pigs.
Division of Virology, Department of Biomedical Sciences and Veterinary Public Health, Swedish University of Agricultural Sciences, Uppsala, Sweden; Centro Nacional de Investigación Disciplinaria en Microbiología Animal, INIFAP, Mexico DF, Mexico. Electronic address: cuevas.julieta@inifap.gob.mx.
S
S
Cuevas-Romero
Facultad de Estudios Superiores Cuautitlán (FES-C), Universidad Nacional Autónoma de México (UNAM), Mexico.
E
E
Hernández-Baumgarten
Veterinary Sciences Division, Agri-Food and Biosciences Institute, Stoney Road, Stormont, Belfast, Northern Ireland, United Kingdom.
S
S
Kennedy
Centro de Investigacion Biomedica de Oriente, IMSS, Metepec, Puebla, Mexico.
P
P
Hernández-Jáuregui
Division of Virology, Department of Biomedical Sciences and Veterinary Public Health, Swedish University of Agricultural Sciences, Uppsala, Sweden.
M
M
Berg
Division of Virology, Department of Biomedical Sciences and Veterinary Public Health, Swedish University of Agricultural Sciences, Uppsala, Sweden.
J
J
Moreno-López
D000825:Animal Structures / Q000821:virology; D000818:Animals; D057134:Antibodies, Neutralizing / Q000097:blood; D000914:Antibodies, Viral / Q000097:blood; D004196:Disease Outbreaks; D004797:Enzyme-Linked Immunosorbent Assay; D009500:Neutralization Tests; D016133:Polymerase Chain Reaction; D012333:RNA, Messenger / Q000302:isolation & purification; D012367:RNA, Viral / Q000302:isolation & purification; D019213:Rubulavirus / Q000302:isolation & purification*; D019351:Rubulavirus Infections / Q000453:epidemiology / Q000662:veterinary* / Q000821:virology; D013552:Swine; D013553:Swine Diseases / Q000453:epidemiology* / Q000821:virology*; D013997:Time Factors; D014764:Viral Proteins / Q000235:genetics
D057134:Antibodies, Neutralizing; D000914:Antibodies, Viral; D012333:RNA, Messenger; D012367:RNA, Viral; D014764:Viral Proteins
Chronic natural infection; Long-term persistence; Porcine rubulavirus; Viral transmission