Circovirus: A genus of the family CIRCOVIRIDAE that infects SWINE; PSITTACINES; and non-psittacine BIRDS. Species include Beak and feather disease virus causing a fatal disease in psittacine birds, and Porcine circovirus causing postweaning multisystemic wasting syndrome in pigs (PORCINE POSTWEANING MULTISYSTEMIC WASTING SYNDROME).Circoviridae Infections: Virus diseases caused by the CIRCOVIRIDAE.Wasting Syndrome: A condition of involuntary weight loss of greater then 10% of baseline body weight. It is characterized by atrophy of muscles and depletion of lean body mass. Wasting is a sign of MALNUTRITION as a result of inadequate dietary intake, malabsorption, or hypermetabolism.Porcine Postweaning Multisystemic Wasting Syndrome: A worldwide emerging disease of weaned piglets first recognized in swine herds in western Canada in 1997. This syndrome is characterized by progressive weight loss, rapid (tachypnea) and difficult (dyspnea) breathing, and yellowing of skin. PMWS is caused by PORCINE CIRCOVIRUS infection, specifically type 2 or PCV-2.Swine Diseases: Diseases of domestic swine and of the wild boar of the genus Sus.Circoviridae: A family of very small viruses containing circular, single-stranded DNA and possessing no envelope. The modes of transmission are not known.Swine: Any of various animals that constitute the family Suidae and comprise stout-bodied, short-legged omnivorous mammals with thick skin, usually covered with coarse bristles, a rather long mobile snout, and small tail. Included are the genera Babyrousa, Phacochoerus (wart hogs), and Sus, the latter containing the domestic pig (see SUS SCROFA).Parvovirus, Porcine: A species of PARVOVIRUS causing reproductive failure in pigs.Porcine respiratory and reproductive syndrome virus: A species of ARTERIVIRUS causing reproductive and respiratory disease in pigs. The European strain is called Lelystad virus. Airborne transmission is common.DNA, Viral: Deoxyribonucleic acid that makes up the genetic material of viruses.Genome, Viral: The complete genetic complement contained in a DNA or RNA molecule in a virus.Porcine Reproductive and Respiratory Syndrome: A syndrome characterized by outbreaks of late term abortions, high numbers of stillbirths and mummified or weak newborn piglets, and respiratory disease in young unweaned and weaned pigs. It is caused by PORCINE RESPIRATORY AND REPRODUCTIVE SYNDROME VIRUS. (Radostits et al., Veterinary Medicine, 8th ed, p1048)Antibodies, Viral: Immunoglobulins produced in response to VIRAL ANTIGENS.Colostrum: The thin, yellow, serous fluid secreted by the mammary glands during pregnancy and immediately postpartum before lactation begins. It consists of immunologically active substances, white blood cells, water, protein, fat, and carbohydrates.Capsid Proteins: Proteins that form the CAPSID of VIRUSES.Viral Vaccines: Suspensions of attenuated or killed viruses administered for the prevention or treatment of infectious viral disease.Bird Diseases: Diseases of birds not considered poultry, therefore usually found in zoos, parks, and the wild. The concept is differentiated from POULTRY DISEASES which is for birds raised as a source of meat or eggs for human consumption, and usually found in barnyards, hatcheries, etc.Weaning: Permanent deprivation of breast milk and commencement of nourishment with other food. (From Stedman, 25th ed)Polymerase Chain Reaction: In vitro method for producing large amounts of specific DNA or RNA fragments of defined length and sequence from small amounts of short oligonucleotide flanking sequences (primers). The essential steps include thermal denaturation of the double-stranded target molecules, annealing of the primers to their complementary sequences, and extension of the annealed primers by enzymatic synthesis with DNA polymerase. The reaction is efficient, specific, and extremely sensitive. Uses for the reaction include disease diagnosis, detection of difficult-to-isolate pathogens, mutation analysis, genetic testing, DNA sequencing, and analyzing evolutionary relationships.Psittaciformes: An order of BIRDS comprised of several families and more than 300 species. It includes COCKATOOS; PARROTS; PARAKEETS; macaws; and BUDGERIGARS.Torque teno virus: A species of non-enveloped DNA virus in the genus ANELLOVIRUS, associated with BLOOD TRANSFUSIONS; and HEPATITIS. However, no etiological role has been found for TTV in hepatitis.Viremia: The presence of viruses in the blood.Open Reading Frames: A sequence of successive nucleotide triplets that are read as CODONS specifying AMINO ACIDS and begin with an INITIATOR CODON and end with a stop codon (CODON, TERMINATOR).Molecular Sequence Data: Descriptions of specific amino acid, carbohydrate, or nucleotide sequences which have appeared in the published literature and/or are deposited in and maintained by databanks such as GENBANK, European Molecular Biology Laboratory (EMBL), National Biomedical Research Foundation (NBRF), or other sequence repositories.