Family Parvoviridae, Porcine Parvovirus

Question 1

Transmission of Porcine Parvovirus

Answer 1

Oro-nasal in the non-immune pregnant sow, followed by transplacental transmission
Veneral transmission is possible, as boars shed the virus in their semen

Question 2

Transplacental infection with PPV

Answer 2

Each fetus/embryo has a separate placenta therefore, not all are infected at the same time
Virus spread through the uterus and infection of the rest of the fetuses/embryos occurs
Hence, death occurring at different stages of pregnancy is typical of PPV infections

Question 3

Sites of viral replication of PPV

Answer 3

Predilection for mitotically active cells in fetal tissue

Replicates in blood lymphoctes, monocytes

Question 4

Hallmark clinical sign of PPV

Answer 4

The increase in mummified fetuses after a normal gestation period is the hallmark of PPV

Question 5

Clinical signs associated with time of infection

Answer 5

Embryo/fetus (70 days) = frequently develop to lesions, but also mount an immune response and usually survive in-utero

Question 6

PPV is the major cause of what type of clinical signs?

Answer 6

SMEDI

Stillbirth, mummification, embryonic death, infertility

Question 7

Immunity of PPV

Answer 7

Passively acquired maternal antibody
Some gilts can become seronegative at time of conceiving and are susceptible to infection
Unlike most parvoviruses, porcine parvovirus can cause persistent infection with periodical shedding of virus

Question 8

Vaccination for PPV

Answer 8

Best way: vaccinate all susceptible breeding stock twice, two weeks apart, several weeks before breeding
Gilts can be naturally infected several weeks before breeding by mingling with older breeding stock that may be shedding the virus