Porcine Circoviruses
Sheela Ramamoorthy and P. Pineyro
from: Porcine Viruses: From Pathogenesis to Strategies for Control (Edited by: Hovakim Zakaryan). Caister Academic Press, U.K. (2019) Pages: 81-106.
Abstract
Porcine circoviruses are small, single stranded DNA viruses belonging to the Circoviridae family. Two major open reading frames (ORF), ORF1 and ORF2, which run in opposing directions on the 1700bp genome, code for the capsid and replicase proteins respectively. Transmission of PCV2 occurs both horizontally via contaminated feed, water or contact and vertically from mother to fetus. Porcine circovirus strain 2 (PCV2) was initially identified as the causative agent of post weaning multi-systemic wasting syndrome in weanling pigs, which is characterized by severe weight loss and lymphadenopathy. Subsequently, a wide range of clinical syndromes such as reproductive failure, respiratory signs and diarrhea were associated with PCV2 infections and are now recognized as a part of porcine circovirus associated diseases or PCVAD. Post-mortem diagnosis of PCVAD requires a combination of the presence of clinical signs and demonstration of PCV2 antigen in tissues or lymph nodes. Ante-mortem diagnosis could involve serological testing for antibodies or detection of viral DNA by PCR in combination with the herd history. Commercial vaccines against PCV2 are effective in preventing clinical signs. They are administered at 3 weeks of age and prior to farrowing in sows. Both vaccination and strict biosecurity measures are critical for the control of PCV2. However, periodical emergence of new viral strains due to mutation and recombination in the field continue to render PCV2 an economically important pathogen of swine read more ...
