Vaccinia viruses isolated from cutaneous disease in horses are highly virulent for rabbits.
Two genotypically distinct Vaccinia viruses (VACV), named P1V and P2V, were isolated from an outbreak of cutaneous disease in horses in Southern Brazil. We herein investigated the susceptibility of rabbits, a proposed animal model, to P1V and P2V infection. Groups of weanling rabbits were inoculated intranasally (IN) with P1V or P2V at low (10(2.5) TCID50), medium (10(4.5)TCID50), or high titer (10(6.5)TCID50). Rabbits inoculated with medium and high titers shed virus in nasal secretions and developed serous to hemorrhagic nasal discharge and severe respiratory distress, followed by progressive apathy and high lethality. Clinical signs appeared around days 3-6 post-inoculation (pi) and lasted up to the day of death or euthanasia (around days 5-10). Virus shedding and clinical signs were less frequent in rabbits inoculated with low virus titers. Viremia was detected in all groups, with different frequencies. Viral DNA was detected in the feces of a few animals inoculated with P1V and P2V, low titer, and with P2V at high titer. Gross necropsy findings and histological examination showed diffuse interstitial fibrousing pneumonia with necrosuppurative bronchopneumonia and intestinal liquid content. Neutralizing antibodies were detected in all inoculated animals surviving beyond day 9 pi. These results show that rabbits are highly susceptible to VACV isolated from horses, and develop severe respiratory and systemic disease upon IN inoculation. Thus, rabbits may be used to study selected aspects of VACV infection and disease.
Setor de Virologia, Departamento de Medicina Veterinária Preventiva, Universidade Federal de Santa Maria, Av. Roraima, 1000 Camobi, Santa Maria, Rio Grande do Sul, CEP 97105-900, Brazil.
Juliana
J
Felipetto Cargnelutti
Candice
C
Schmidt
Eduardo Kenji
EK
Masuda
Lisiane Danusa
LD
Braum
Rudi
R
Weiblen
Eduardo
E
Furtado Flores
D000818:Animals; D001938:Brazil / Q000453:epidemiology; D004279:DNA, Viral / Q000302:isolation & purification; D004195:Disease Models, Animal; D004196:Disease Outbreaks; D005243:Feces / Q000821:virology; D006734:Horse Diseases / Q000453:epidemiology* / Q000821:virology*; D006736:Horses; D017563:Lung Diseases, Interstitial / Q000150:complications / Q000473:pathology / Q000821:virology; D018155:Orthopoxvirus / Q000302:isolation & purification* / Q000472:pathogenicity*; D011213:Poxviridae Infections / Q000453:epidemiology / Q000473:pathology / Q000662:veterinary* / Q000821:virology; D011817:Rabbits; D012128:Respiratory Distress Syndrome / Q000401:mortality / Q000473:pathology / Q000821:virology; D012220:Rhinitis / Q000150:complications / Q000473:pathology / Q000821:virology; D017193:Skin Diseases, Viral / Q000453:epidemiology / Q000473:pathology / Q000662:veterinary* / Q000821:virology; D016019:Survival Analysis; D014766:Viremia / Q000401:mortality / Q000473:pathology / Q000821:virology
D004279:DNA, Viral