14. Pneumoenteritis of ruminants caused by adenoviruses. Flashcards
4 important adenoviruses types?
Genera: 4 main important ones
- Mastadeno- (most important for us, it contains the mamarrioadenovirus),
- aviadeno- (1 or 2 avian diseases)
- atadeno- (also important)
- siadeno-, ichtadenovirus (last 2 also avian, reptile and fish diseases but are less important) genus
- Species: named by letters (A, B, C…)
Serotypes and Virus Morphology?
- Serotypes: numbered (from 1, based on VN)
- Serogroups: based on cross reactions between serotypes (AGID, CF)
- Virus morphology:
- dsDNA genome, icosahedral symmetry (80-110nm)
- No envelope - relatively resistant
- Surface projections: fibres ʹ neutralising antigen
Resistance?
- Resistance:
- relatively resistant
- pH 3-10, up to 60C survives
- Sensitive to formaldehyde, acids, bases
- Resistant to iodophores and detergents
Biological properties?
Biological properties:
- Wide distribution - but not in cats (except immune suppressed)
- Diverse pathogenicity - frequent asymptomatic carriage
- But pathogenicity is relatively low
- Vet impo: CAV, BAV, and some avian AV - no more than 4
Oncogen effect?
Oncogen effect
- but never cause tumours
- so the oncogenic effect is based on the genetic testing of the virus and in lab mice can cause tumors,
- but never happens in the host
Antigenic properties?
Antigenic properties:
- Strong antigens - survival of the infection will result in very long immunity. So usually above a
- certain age, the animals are resistant to the infection
- Cross-reactions within genus - serogroups
- Results in group-specific antibody secretion
- In certain cases, causes cross-immunity. E.g. Canine laryngotracheitis which is a mildly
- pathogenic widespread virus will result in immunity against the canine hepatitis because
- of cross-reaction (if the animal survives)
- So clinical cases of canine hepatitis are extremely rare
Diagnostics?
Diagnostics:
- Virus isolation (strong CPE), IF, HA, ELISA, PCR (PCR is true for all of the viruses - direct)
- Indirect: VN, ELISA, AGID (Agar immune diffusion), CF, HAI
Adenovirus pneumoenteritis in calves?
Adenovirus pneumoenteritis in calves
- Dog is most important, then comes calf
- Part of BCRDS - bovine chronic respiratory disease syndrome
- Adenoviruses alone are not important - become important when part of a syndrome
- Immune suppression is the first step, then usually virus (adeno, parainfluenza, herpes, rio, etc.)
- which damage the resp epith surface, then secondary bacterial (mannheimia, pasteurella,
- histophilus etc.) - the problem turns chronic due to the bacteria phase
- Mild disease of 1-4m old calves with nasal discharge, coughing and diarrhea
Adenovirus pneumoenteritis in calves causative agent?
Causative agents:
Mastadenovirus genus:
“Subgroup I.” - Replication in bovine kidney cells
Atadenovirus genus
“Subgroup 2” Replication in bovine testicle cells
Epizootiology of Adenovirus pneumoenteritis in calves?
Epizootiology
- Intro to a farm with carrier calves
- Usually in large farms (crowding) - pretty much all large farms are infected
- Fattening farms which are purchasing young calves from many sources
- Poor colostrum uptake
- In adult cattle subclinical
- Role of co-infections (BVD, IBR, PI-3, Pasteurella, etc.)
Pathogenesis of adenovirus pneumoenteritis of calves?
Pathogenesis
- PO, air-borne infection
- Multiplication in tonsils
- Viraemia (lymphoid cells): respiratory, enteric mucosal epithelia
Clinical signs of adenovirus pneumoenteritis of Calves?
Clinical signs
- From 6-8 weeks of age onwards (without colostrum from 3-4 weeks onwards)
- Incubation period: 1-7 days
- Mild fever, loss of appetite, conjunctivitis, serous nasal discharge
- Coughing, salivation, mild diarrhoea
- Co-infections 1-2 weeks after first signs ➝ pneumonia
Pathology, Histopath of Pneumoenteritis of calves?
Pathology, histopath
- Intralobular interstitial pneumonia
- Bronchiolitis, atelectasia
- Virus enteritis, osmotic diarrhoea
- Kidney tubular epithelial necrosis ➝ release ➝ proteinuria
- BAdV-10
‣ New Zealand, Northern Ireland
‣ Non-febrile enterocolitis, haemorrhagic gastroenteritis, haemorrhages in renal cortex, bladder and trachea
- Intranuclear inclusion bodies
Diagnosis, Treatment and Prevention of pneumoenteritis of calves?
Diagnosis
- Virus isolation
- IF, ELISA, PCR
- Serology: VN (paired sera investigations) - with all serotypes
Treatment:
- Symptomatic and supportive therapy (with ABs)
x Prevention
- There is no vaccine ʹ not allowed to used
- Improve keeping conditions, improve/ensure colostrum uptake!
Pneumovirus pneumoenteritis in lambs Causative agent, Epidemiology?
Pneumovirus pneumoenteritis in lambs
- Very similar to calf, just replace calf with lamb
- Resp and enteric disease usually in intensively raised lambs
Causative agents:
- Mastadenovirus genus, Atadenovirus
Epidemiology: : same as calves
- Mainly in lambs of young ewes (first pregnancy)
- Crowded raising/fattening farms
- Frequent asymptomatic carriage
