Parvoviridae PDF

VETERINARY VIROLOGY PARVOVIRIDAE Butay, Dian Dane, Diaz, Kenneth Francisco, Marc Ramos, Mark John Rubiaco, Sean Wayne Sanut, Johann Zseus  History:  1900s-Enteritis, Panleukopenia, Congenital Cerebellar Ataxia epidemics in Cats (Feline FP)  1947-Similar...

VETERINARY VIROLOGY PARVOVIRIDAE Butay, Dian Dane, Diaz, Kenneth Francisco, Marc Ramos, Mark John Rubiaco, Sean Wayne Sanut, Johann Zseus  History:  1900s-Enteritis, Panleukopenia, Congenital Cerebellar Ataxia epidemics in Cats (Feline FP)  1947-Similar syndrome observed in minks (mink enteritis)  mid-1960s-Virus causing FP and mink enteritis shown to belong to same family of small naked DNA viruses  1965-Parvovirus Propose  1970s-New syndrome of viral enteritis and myocarditis in dogs (canine parvovirus  Early 1980s-Human parvovirus (B19) found to cause several diseases (transient aplastic anemia)  Classification: Subfamily Genus Characteristics Parvovirus minute virus of mice infects vertebrates canine parvovirus 1,2- and replicates porcine parvovirus autonomously -feline parvovirus -mink enteritis virus -duck parvovirus bovine parvovirus Parvoviridae Erythrovirus *human parvovirus human and simian parvovirus Dependovirus adeno-associated (adeno-associated virus 1,2* viruses) requires co- infection with unrelated virus(helper) for producing infections  Virion Morphology and Structures:  Non-enveloped, icosahedral, 25 nm diameter  Virions are extremely stable in environmental conditions (60C for 60 mins; pH3-9)  Viral Genome and Proteins:  Genome: linear, ss DNA, 5.2 kbp in size  Proteins: -non-structural: NS1, NS2 -structural: VP1, VP2 VP3 Properties attributed to VP2; host species and tissue tropism, receptor binding, antigenic properties.  Viral Replication:  Replication occurs in the nucleus.  Virus requires dividing host cells undergoing DNA replication (S-phase).  Entry: receptor-mediated endocytosis  Diseases Caused by Parvoviruses: Principles for understanding parvovirus Infections and disease 1. Near absolute requirement for dividing cells as host 2. Identification of target cell defines pathogenesis:  -heart = myocarditis in puppies, gooselings  -cerebellum=ataxia in kittens  -Intestine = enteritis in adult dogs  -liver = hepatitis in adult hamsters and geese  -bone marrow = erythrocyte aplasia in humans 3. Capsid coding sequences define host range and pathogenicity  Parvovirus diseases in animals and humans Virus Disease Feline Generalized Neonatal Disease, Cerebellar Virus (FPV), Hypoplasia, Panleukopenia Panleukopenia, Enteritis Canine Parvovirus Generalized Neonatal Disease; Enteritis, Myocarditis,Leukopenia 2 Porcine Parvovirus SMEDI Feline Panleukopenia:  Feline panleukopenia virus has an almost identical DNA sequence as canine parvovirus; however, this virus does not harm dogs. Instead, feline panleukopenia causes disease in all felids, as well as in some members of related families, such as raccoons or minks. This virus is commonly referred to as feline distemper and causes fever, low white blood cell count, diarrhea, and sometimes even death. Virus Pathogenesis  FPV infects and destroys actively dividing cells in bone marrow, lymphoid tissues, intestinal epithelium, and—in very young animals—cerebellum and retina. In pregnant queens, the virus may spread transplacentally to cause embryonic resorption, fetal  mummification, abortion, or stillbirth. Alternatively, infection of kittens in the perinatal period may destroy the germinal epithelium of the cerebellum, leading to cerebellar hypoplasia, incoordination, and tremor. Presumptive Diagnosis (non-specific)  Clinical signs  hematological exam  Pathology Treatment  IV Fluid B  Vitamins  Plasma  Antibiotic  Anthelmintics  Antiemetics Control  Stability of virus and high amount of virus excreted (up to 109 ID50/g of feces) makes disinfection difficult.  Vaccination: live and killed virus vaccines.  Maternal antibodies interfere with vaccination. Canine Parvovirus:  Canine parvovirus type 2 (CPV-2) emerged in late 1970s, during which it caused severe epizootics in kennels and dog shelters worldwide and soon became endemic in the global dog population. Parvoviruses in dogs are potentially fatal infections that can damage the intestines and cause severe diarrhea and dehydration. Virus Pathogenesis  Viral entry through oronasal route -> Multiplication in LNs in throat -> Viremia in 3- 5 days after infection -> localizes in GIT epithelium, small intestine, bone marrow, myocardium. Presumptive diagnosis (non-specific)  Signalment (characteristic marks) History -Presenting signs Fecal viral antigen testing or Viral PCR testing. Treatment   There is no cure for parvoviral enteritis. However, supportive treatments are administered This requires the administration of intravenous fluids containing electrolytes. (D5LRS, LRS etc.) In severe cases, plasma transfusions may be given. Antibiotics and anti-inflammatory drugs are given to prevent or control septicemia. Anti- emetic drugs to relieve dog from vomiting. Control  Vaccination as early as 6-8 weeks after deworming. Healthy dogs should receive 3 doses, each administered 3 weeks apart although protocol may vary from clinic to clinic. Porcine Parvovirus:  Porcine parvovirus is the major causative virus in a reproductive failure syndrome in swine. The characteristic symptoms of porcine parvovirus are grouped under the acronym SMEDI. To this end, SMEDI stands for stillbirths, mummified fetuses, early embryonic death, and infertility. This infection has been reported to occur worldwide with variable prevalence rates. Virus Pathogenesis  The virus replicates initially in tonsils after which it reaches the lymphatic system leading to cell-free viremia. Placental cells do not support porcine parvoviral infection nor can the virus cross the epitheliochorial placenta Presumptive diagnosis (non-specific)  PPV antigen in the lungs using immunofluorescent microscopy. Preferred specimen from fetus ’lungs. Treatment  No Treatment Control  Killed vaccines used twice, 2 weeks apart. References:  Sanchez RE. 2005. Course Module in Vetrinary Virology.  Sykes, J.E. (2013). Canine Parvovirus Infections and Other Viral Enteritides. Canine and Feline Infectious Diseases, 141 - 151.  https://www.news-medical.net/health/Types-of- Parvovirus.aspx?fbclid=IwZXh0bgNhZW0CMTEAAR1e9ClpYpu27HPDFsK0nmVA40E- 6fpb9D9sgCt5ykrnEpx4uoYNJlMR1ao_aem_pFmsReytEZsD_mRAZ1gtDw