Infectiousness of pigs infected by the Porcine Reproductive and Respiratory Syndrome virus (PRRSV) is time-dependent

The time-dependent transmission rate of Porcine Reproductive and Respiratory Syndrome Virus (PRRSV) and the correlation between infectiousness, virological parameters and antibody responses of the infected pigs were studied in experimental conditions. Seven successive transmission trials involving a...

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Published in:	Veterinary research (Paris) Vol. 43; no. 1; p. 69
Main Authors:	Charpin, Céline, Mahé, Sophie, Keranflec'h, André, Belloc, Catherine, Cariolet, Roland, Le Potier, Marie-Frédérique, Rose, Nicolas
Format:	Journal Article
Language:	English
Published:	England BioMed Central Ltd 12-10-2012 BioMed Central BMC
Subjects:	Animals Antibodies Antibodies, Neutralizing - blood Antibodies, Viral - blood Care and treatment Diagnosis Disease transmission Enzyme-Linked Immunosorbent Assay - veterinary Genome, Viral Genomics Health aspects Infection Life Sciences Models, Biological Nose - virology Physiological aspects Polymerase chain reaction Polymerase Chain Reaction - veterinary Porcine reproductive and respiratory syndrome Porcine Reproductive and Respiratory Syndrome - transmission Porcine Reproductive and Respiratory Syndrome - virology Porcine respiratory and reproductive syndrome virus - genetics Porcine respiratory and reproductive syndrome virus - immunology Random Allocation Specific Pathogen-Free Organisms Swine Time Factors Viral antibodies Virus Shedding France Basic Reproduction Ratio Contact Group Nasal Swab Genome Load Classical Swine Fever Virus
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Summary:	The time-dependent transmission rate of Porcine Reproductive and Respiratory Syndrome Virus (PRRSV) and the correlation between infectiousness, virological parameters and antibody responses of the infected pigs were studied in experimental conditions. Seven successive transmission trials involving a total of 77 specific pathogen-free piglets were carried out from 7 to 63 days post-inoculation (dpi). A semi-quantitative real time RT-PCR was developed to assess the evolution of the viral genome load in blood and nasal swabs from inoculated and contact pigs, with time. Virus genome in blood was detectable in inoculated pigs from 7 to 77 dpi, whereas viral genome shedding was detectable from nasal swabs from 2 to 48 dpi. The infectiousness of inoculated pigs, assessed from the frequency of occurrence of infected pigs in susceptible groups in each contact trial, increased from 7 to 14 dpi and then decreased slowly until 42 dpi (3, 7, 2, 1 and 0 pigs infected at 7, 14, 21, 28 and 42 dpi, respectively). These data were used to model the time-dependent infectiousness by a lognormal-like function with a latency period of 1 day and led to an estimated basic reproduction ratio, R0 of 2.6 [1.8, 3.3]. The evolution of infectiousness was mainly correlated with the time-course of viral genome load in the blood whereas the decrease of infectiousness was strongly related to the increase in total antibodies.
Bibliography:	ObjectType-Article-1 SourceType-Scholarly Journals-1 ObjectType-Feature-2 content type line 23 PMCID: PMC3497607
ISSN:	1297-9716 0928-4249 1297-9716
DOI:	10.1186/1297-9716-43-69