The growth and persistence of foot-and-mouth disease virus in the bovine mammary gland

Abstract

SUMMARYIn animals exposed to foot-and-mouth disease virus by indirect contact, virus was recovered from the blood, milk, pharynx, vagina and rectum for variable periods of time before clinical disease was apparent. Virus instilled into the mammary gland multiplied rapidly and virus concentrations greater than 107 p.f.u./ml. were recorded within 8-32 hr., depending on the virus strain and dose inoculated. Virus multiplication was accompanied by clinical signs of mastitis but the classical signs of foot-and-mouth disease did not appear for 52-117 hr. Dissemination of virus from the mammary gland occurred within 4-24 hr. and in some animals samples taken from the pharynx, mouth, nose and vagina contained virus for periods up to 97 hr. before the appearance of vesicular lesions. Virus production in the udder declined with the appearance of virus neutralizing activity in the blood and the milk but persisted in some animals for periods of 3-7 weeks. The ability of foot-and-mouth disease virus to persist in mammary tissue was confirmed by the demonstration of virus multiplication in the udders of immune animals.

Effect of heat on foot-and-mouth disease virus (FMDV) in the components of milk from FMDV-infected cows

“…As was reported earlier by Burrows et al (1971) and by Hyde et al (1975), milk secreted during the prodromal stage of FMD contains large amounts of virus. It is this milk that would be delivered to processing plants and placed into general distribution before the disease could be detected.…”

“…or longer. Significant concentrations of virus in skim milk and cream were partly expected because of the reported recoveries of virus in whole milk by Burrows et al (1971) and later by Hyde et al (1975). The lowest concentration of virus recovered in each instance was obtained from the pelleted cellular debris.…”

Vesicular Exocytosis of Foot-and-Mouth Disease Virus from Mammary Gland Secretory Epithelium of Infected Cows

“…The detection of FMD virus in milk samples from infected cows was the basis for a report by Burrows et al (1971) on the replication of the virus in the mammary gland. Their findings were corroborated by those of J. H. Blackwell & T. Yilma (1981) who reported the observation of FMD virus in fluorescent antibody-labelled and haematoxylin and eosin (HE)-stained secretory cells from the mammary gland of FMD virus-infected lactating cows.…”

Swine vesicular disease: attempts to transmit infection to cattle and sheep

“…Five days after the removal of the pigs the milking cows were re-exposed to infection by the instillation of 1070 p.f.u. of virus into one quarter of the mammary gland (Burrows et al 1971). …”