Studies on the pathogenesis of rinderpest in experimental cattle: IV. Proliferation of the virus following contact infection

Abstract

Cattle were infected with rinderpest virus by housing them for 24 hr. in stalls containing donor animals which had been reacting to the disease for 3–5 days. They were then transferred to individual clean stalls and killed on the 2nd to 10th days following first exposure. Various tissues were collected, particularly those of the upper and lower respiratory tracts, and their virus content was estimated in calf-kidney tissue cultures.Virus was recovered from 15 of 35 animals tested and in eight of these generalization had occurred, although only two had begun to show a pyrexial response. The stage of the infection could not be predicted from the time that had elapsed following exposure, since early, limited proliferation was encountered on the 3rd to the 10th days.It was considered that seven animals gave indications of the pathways by which natural infection had occurred. In each of these virus proliferation was established very early in the pharyngeal lymph node; in three the submaxillary lymph node was similarly involved and in four the palatal tonsil. It was suggested that these data probably indicated that infection always occurred via the upper respiratory tract.In three cases virus titres were highest in the bronchial or costocervical lymph nodes; this was construed as evidence for the additional involvement of the lower respiratory tract in primary infection.No infectivity could be demonstrated in the mucosae or lung parenchyma associated with the above-mentioned lymph nodes and this, together with previously published data, was accepted as strong presumptive evidence that the infecting virus passes through the mucosae without producing a local lesion or proliferating there. These results were compared briefly with those of Bedson & Duckworth (1963) for rabbit pox.

The growth of a virulent strain of African swine fever virus in domestic pigs

“…The primary establishment of virus in the bronchial mucosa and associated lymph nodes of two pigs, with or without the involvement of the retropharyngeal route, suggests that infection by aerosols of small particle size can probably occur via the lower respiratory tract. This could be an alternative route of natural infection, as shown already for rabbit-pox (Bedson & IDuckworth, 1963) and rinderpest in cattle (Taylor et al 1965). It is necessary to observe, however, that transmission of ASFV by expired air could not be demonstrated by Montgomery (1921), even over a distance as short as 6 in.…”

Rinderpest virus expressing enhanced green fluorescent protein as a separate transcription unit retains pathogenicity for cattle

“…Experimental studies with other strains of RPV have also shown that whilst morbidity rates are often very high, mortality rates can vary between 30 and 90 % depending on the infecting strain (Taylor, 1986). It is accepted that correlates of pathogenicity are poorly understood for the morbilliviruses with both immune status of the host and genetic background of the infecting virus playing roles in the outcome of infection (Taylor et al, 1965;Taylor, 1986;Wamwayi et al, 1995). Using this approach with the virulent virus showed that inclusion of a heterologous gene between the P and M genes is tolerated and that the pathogenic potential of the resultant virus is comparable to that of the wild-type parent.…”

“…In such cases, PCR analysis will always be more sensitive. Historic experiments with greater numbers of animals have shown that the infection is not 100 % fatal and that some animals that develop severe disease may still clear the virus and go on to convalesce (Taylor et al, 1965;Taylor, 1986;Wamwayi et al, 1995). Studies with greater numbers of animals would be needed to determine if the rate of virus clearance is related to convalescence in cattle infected with this virus.…”