1887

Abstract

SUMMARY: Seven phages were fairly susceptible to the lethal effect of acidified whey, more so than the enteropathogenic strains on which they were active. The low acidity that prevailed in the abomasum contents of calves shortly after a milk feed had little harmful effect on orally administered organisms of these phages; they flooded into the small intestine. The high acidity that prevailed later was lethal to orally administered phage organisms; few entered the small intestine. The lethal effect could be counteracted by giving CaCO in the feed. Low concentrations of phage-neutralizing antibodies were found in some serum samples from human beings, cattle and pigs. Antibodies to one of the seven phages were common in the human samples and antibodies to another, phage B44/1, were common in the cattle and pig samples and in bovine colostrum. Phage B44/1 antibodies in a sample of colostral whey were destroyed at pH 3·25 or less. Giving colostrum containing phage B44/1 antibodies with CaCO to a calf greatly reduced the numbers of orally administered phage B44/1 organisms in its alimentary tract. Antibodies to another phage were induced in the serum of a calf suffering from diarrhoea by treating it with that phage. The phages were as susceptible as the strains to the lethal action of formaldehyde and sodium hypochlorite. In contrast to the strains, they were almost completely resistant to phenol and chloroxylenol. The virulence of 21 phages varied according to the temperature at which tests were performed. The majority were almost avirulent at 20 °C and 43 °C and most virulent at 37 °C. Experiments in calves suggested that their body temperatures were sufficiently high to adversely influence the virulence of some phages.

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/content/journal/micro/10.1099/00221287-133-5-1127
1987-05-01
2019-10-23
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