Bovine rhinovirus infection

G R THOMSON

GENERAL INTRODUCTION: PICORNAVIRIDAE

Introduction and aetiology

Bovine rhinovirus infection is probably ubiquitous in cattle populations, but its association with disease is uncertain.

The virus was first identified in Germany by Bögel and Böhm in 1962, and it has subsequently been found in England, the USA, Japan and Sudan. Three serotypes (1, 2 and 3) have been identified.^{3, 8, 10}

Apart from their typical picornavirus morphology and physicochemical characteristics,^{4, 6} bovine rhinoviruses have features common to all rhinoviruses — instability at pH 3,0 to 3,6, optimal replication in slightly acidic or neutral medium at 30 to 34 °C, resistance to treatment with ether and chloroform, and lack of stabilization by 1M MgCl₂ when heated to 50 °C for 60 minutes.^{3, 4, 7, 9, 10}

There are conflicting reports about the ease with which bovine rhinoviruses can be cultivated in cell cultures, the variation probably being due to differences inherent in different viruses.⁷ One virus isolation was only achieved after eight passages in calf tracheal organ cultures whereafter the virus was adapted to growth in monolayers of primary bovine kidney cells.⁷ In other cases isolation, usually in bovine kidney cultures, has been achieved without difficulty, ^{2, 4, 9} although it may take up to nine days for cytopathic effects to develop on primary isolation. The rolling of cell cultures may be advantageous to viral replication and the production of cytopathic effects.^{4, 9}

Epidemiology, clinical signs, pathogenesis, pathology and control

It is presumed that bovine rhinoviruses are transmitted directly between the upper respiratory tracts of cattle because viral isolations have been made only from the nasal and tracheal secretions of infected cattle. The quantities of virus present in the nasal secretions of acutely infected animals are probably low as dilution of specimens often results in their failure to yield virus in culture.³

Attempts to isolate the virus from blood and faeces have failed.³

The prevalence of infection in cattle populations is largely unknown, but 48 per cent of cattle in one study in Maryland (USA) were found to contain neutralizing antibody to the virus.⁵ Many infections do not produce obvious disease,^{5, 8} but experimental infection has provided evidence that at least some bovine rhinoviruses are able to cause acute rhinitis in calves^{1, 2} that is accompanied by fever, depression, inappetence, lachrymation, conjunctivitis and serous nasal discharge.⁸ Whether these viruses may also cause lower respiratory tract disease accompanied by coughing and dyspnoea is uncertain because, although lung consolidation, collapse and emphysema have been associated with bovine rhinovirus infection,⁵ there is no unequivocal proof that bovine rhinovirus was the cause. These lesions were characterized microscopically as interstitial pneumonia.^{1, 2}

It is possible that bovine rhinovirus may interact with other infectious agents to cause respiratory disease but there is no categorical evidence for this.³

The diagnosis of bovine rhinovirus infection can at present only be made on the basis of isolation of the virus from the upper respiratory tract of cattle using kidney cell cultures of bovine origin, or foetal or calf tracheal organ cultures. However, because some viruses are apparently poorly adaptable to growth in vitro and the quantities of virus in upper respiratory tract secretions is low, this may not always be possible.^{3, 7}

Serological diagnosis is usually performed using neutralization tests³ but may be complicated by the low levels of antibody induced by these viruses.⁵

Other infectious agents which may be associated with acute upper respiratory tract disease in cattle include bovine respiratory syncytial virus, parainfluenza virus 3, infectious bovine rhinotracheitis (bovine herpesvirus 1), and adenoviruses.

No control of this infection has so far been deemed necessary.⁵

References

1. betts, o.a., edington, n., jennings, a.r. & reed, s.e., 1971. Studies on a rhinovirus (EC11) derived from a calf. II. Disease in calves. Journal of Comparative Pathology, 81, 41–48.
2. ide, p.r. & darbyshire, j.h., 1972. Studies with a rhinovirus of bovine origin. III. The pathogenesis and pathology of infection with strain RS 3x in calves. Archiv fu¨r die gesamte Virusforschung, 36, 335–342.
3. kurogi, h., inaba, y., goto, y., takahashi, a., sato, k., omori, t. & matumoto, m., 1974. Isolation of rhinovirus from cattle in outbreaks of acute respiratory disease. Archiv fu¨r die gesamte Virusforschung, 44, 215–226.
4. lupton, h.w., smith, m.h. & frey, m.l., 1980. Identification and characterization of a bovine rhinovirus from Iowa cattle with acute respiratory tract disease. American Journal of Veterinary Research, 41, 1029–1034.
5. mohanty, s.b., 1973. New herpesviral and rhinoviral respiratory infections. Journal of the American Veterinary Medical Association, 163, 855–857.
6. pereira, h.g., 1989. Picornaviridae. In: porterfeld, j.s., (ed.). Andrew’s Viruses of Vertebrates. 5th edn. London, Philadelphia: Bailliere Tindall.
7. rheed, s.e., tyrrell, d.a.j., betts, o.a. & watt, r.g., 1971. Studies on a rhinovirus (EC11) derived from a calf. I. Isolation in calf tracheal organ cultures and characterization of the virus. Journal of Comparative Pathology, 81, 33–40.
8. sellers, r.f., 1990. Bovine rhinoviruses. In: dinter, z. & morein, b., (eds). Virus Infections of...