The course of hepatitis E virus infection in pigs after contact-infection and intravenous inoculation.
BACKGROUND
Worldwide, hepatitis E virus (HEV) genotype 3 is observed in pigs and transmission to humans is implied. To be able to estimate public health risks from e.g. contact with pigs or consumption of pork products, the transmission routes and dynamics of infection should be identified. Hence, the course of HEV-infection in naturally infected pigs should be studied.


RESULTS
To resemble natural transmission, 24 HEV-susceptible pigs were infected either by one-to-one exposure to intravenously inoculated pigs (C1-pigs; n = 10), by one-to-one exposure to contact-infected pigs (C2-pigs: n = 7; C3-pigs: n = 5) or due to an unknown non-intravenous infection route (one C2-pig and one C3-pig). The course of HEV-infection for contact-infected pigs was characterized by: faecal HEV RNA excretion that started at day 7 (95% confidence interval: 5-10) postexposure and lasted 23 (19-28) days; viremia that started after 13 (8-17) days of faecal HEV RNA excretion and lasted 11 (8-13) days; antibody development that was detected after 13 (10-16) days of faecal HEV RNA excretion. The time until onset of faecal HEV RNA excretion and onset of viremia was significantly shorter for iv-pigs compared to contact-infected pigs, whereas the duration of faecal HEV RNA excretion was significantly longer. At 28 days postinfection HEV RNA was detected less frequently in organs of contact-infected pigs compared to iv-pigs. For contact-infected pigs, HEV RNA was detected in 20 of 39 muscle samples that were proxies for pork at retail and in 4 of 7 urine samples.


CONCLUSIONS
The course of infection differed between infection routes, suggesting that contact-infection could be a better model for natural transmission than iv inoculation. Urine and meat were identified as possible HEV-sources for pig-to-pig and pig-to-human HEV transmission.
Bouwknegt
Martijn
M
Laboratory for Zoonoses and Environmental Microbiology, Centre for Infectious Disease Control Netherlands, National Institute for Public Health and the Environment, Bilthoven, The Netherlands. martijn.bouwknegt@rivm.nl
Rutjes
Saskia A
SA
Reusken
Chantal B E M
CB
Stockhofe-Zurwieden
Norbert
N
Frankena
Klaas
K
de Jong
Mart C M
MC
de Roda Husman
Ana Maria
AM
Poel
Wim H M van der
WH
D000410:Alanine Transaminase / Q000097:blood; D000818:Animals; D001219:Aspartate Aminotransferases / Q000097:blood; D001646:Bile / Q000737:chemistry; D005243:Feces / Q000821:virology; D006508:Hepatitis Antibodies / Q000097:blood; D016751:Hepatitis E / Q000473:pathology / Q000635:transmission / Q000662:veterinary* / Q000821:virology; D016752:Hepatitis E virus / Q000502:physiology*; D007275:Injections, Intravenous; D008099:Liver / Q000473:pathology; D018482:Muscle, Skeletal / Q000737:chemistry; D012367:RNA, Viral / Q000032:analysis / Q000652:urine; D013552:Swine; D013553:Swine Diseases / Q000473:pathology / Q000635:transmission* / Q000821:virology; D013997:Time Factors; D014766:Viremia / Q000635:transmission / Q000662:veterinary / Q000821:virology
D006508:Hepatitis Antibodies; D012367:RNA, Viral; D001219:Aspartate Aminotransferases; D000410:Alanine Transaminase