Neonatal diarrhoea Rota and coronaviruses October 6, 2010

Viral causes of diarrhoea in neonates Rotavirus Coronavirus BVD Bredavirus Calicivirus Parvovirus Astrovirus

Susceptibility of neonates Rotaviruses 4 to 14 days Coronavirus 4 to days Colostral Antibodies in gut Susceptible period

Prevention of viral diarrhea in calves Vaccination of pregnant animals Colostrum for 2 weeks Management

vaccines against calf diarrhoea

Rotaviruses

Viruses with ds RNA genomes Reoviridae Birnaviridae rotaviruses bluetongue virus african horse sickness infectious bursal disease (chickens) infectious pancreatic necrosis (salmonid fish)

Rotaviruses 7 groups and many serotypes DS, segmented genome Unenveloped Inactivated by phenolic disinfectants Relatively insensitive to chlorination Persistence?

Rotavirus structure, serogroups and serotypes VP4 VP7 VP6 VP3 VP2 VP1 7 Groups (A->G) 14 serotypes (G) 12 serotypes (P)

Segmented genomes of rotaviruses implications electropherotyping

Bovine rotaviruses Group A > B>C Most Group A, serotypes G6 and G10

Pathogenesis lactase water Undigested milk Shortened and fused villi

Maintenance of rotaviruses in populations stable in environment mucosal antibody more important than systemic antibody persistence and periodic shedding

Diagnosis Detection of virus in fecal smears by FAT –FAT for GrA (PDS) feces, $22 includes coronavirus jejunum, ileum, $38.50, includes coronavirus EM and immune EM antigen capture ELISAs (human test for Gr A rotaviruses) –80 to 95% sensitivity and specificity compared to RT- PCR (Maes et al. 2003, J. clin micro 41:290)

Coronaviruses

Viruses with +ve RNA genomes Picornaviridae Caliciviridae Coronaviridae Arteriviridae Flaviviridae Togaviridae foot and mouth disease virus porcine enteroviruses feline calicivirus equine arterivirus pestiviruses (BVD) coronaviruses equine encephalitis viruses

Coronaviruses SS +ve RNA Enveloped Epithelial cells of gut and respiratory tract Persistent infections Increased shedding in winter and at calving (bovine corona virus)

Diagnosis FAT on fecal or gut samples ($ /sample) EM ($45/sample)

Some other coronaviruses Transmissible gastroenteritis and respiratory disease in pigs Infectious bronchitis in poultry Feline enteric coronavirus (FEC) and infectious peritonitis (FIP) Ferret (catarrhal enteritis and FIP-like) SARS coronavirus

feline infectious peritonitis M.C. Horzinek and H. Lutz An update on FIP Veterinary Sience Tomorrow Jan,

FIP fatal disease of young (3-18 mo), or very old in multi-cat houses or catteries not seen before 1950 –new virus? –old virus, new disease systemic antibodies not protective, may even be harmful

feline enteric coronavirus closely related to dog, pig (TGE), human coronaviruses –species specific but K9CV can infect cats two serotypes –serotype I –more common, 70-95% of isolates, does not cross react with K9CV –difficult to isolate

FeCV, serotype 2 Both serotypes can lead to FIP causing strains

epidemiology Exposure to FeCV –25% of cats from 1-2 cat households are seropositive –75-100% of cats from catteries seropositive susceptible cats become infected immediately following exposure kittens can become infected in utero or soon after maternal antibodies drop below protective levels

epidemiology (FIP) 1:5,000 in 1-2 cat households 1:20 in catteries –sporadic –clustered (2-3 cats) - rare –rarely epidemic no gender or breed predisposition

FIP pathogenesis FEC Mild diarrhoea or respiratory illness persistent infection virusimmune system low level of replication in epithelial and lymphoid cells

pregnancy in young queens elective surgery weaning, sale, shipment, adoption concurrent infections (FeLV, FIV ?)

Virus immune system increased virus replication -> virulent mutants increased ability to grow in macrophages immune-mediated lysis of infected cells cytokines draw in more susceptible cells vascular permeability immune complex related damage

M.C. Horzinek and H. Lutz An update on FIP Veterinary Sience Tomorrow Jan,

clinical signs common signs –chronic antibiotic unresponsive fever –progressive anorexia, weight loss –stunting of growth blood abnormalities –progressive increase in serum proteins –increase in globulins –anemia –serum, urine brown due to bilirubin

clinical signs “wet” form (poor cell-mediated immunity) –peritonitis –pleuritis “dry” form (some CMI) granulomas enlarged lymph nodes cloudiness in eye neurological signs can change from dry to wet Sharif et al Vet Med Int

diagnosis RT-PCR for FeCoV Serology (ELISA for anti FeCoV antibodies) –prognosis? no titre - no FIP but may still be infected <100 - less chance of developing FIP >100 - greater chance of getting FIP increased globulins and protein (>35g/L) cytology –degenerate and non-degenerate PMN, macrophages, some lymphocytes, protein background –FeCV positive cells (FAT)

control vaccine –Primucell FIP Intranasal ts virus management –early weaning and separation