Genomic Sequence of a Megrivirus Strain Identified in Laying Hens in Brazil.

A new strain of chicken megrivirus was identified in fecal samples of layer chickens in a commercial flock in Minas Gerais, Brazil. It is most closely related to the family Picornaviridae, genus Megrivirus, species Melegrivirus A, and has an overall nucleotide identity of up to 85.1% with other megrivirus strains.

Comparison of commercial enzyme-linked immunosorbent assays and fluorescent microbead immunoassays for detection of antibodies against porcine reproductive and respiratory syndrome virus in boars.

The objective of this study was to compare the ability of two commercial enzyme-linked immunosorbent assays (ELISAs) and an in-house fluorescent microbead immunoassay (FMIA) to detect IgG antibodies against porcine reproductive and respiratory syndrome virus (PRRSV) types 1 and 2 in serum and oral fluids from boars infected experimentally. Samples from uninfected control pigs and PRRSV-negative field samples were also used. Serum samples were tested by ELISAs (IDEXX Se, HIPRA Se) and an in-house FMIA-Se for detection of PRRSV types 1 and 2. Oral fluids were tested by ELISAs (IDEXX-SO, IDEXX-OF, HIPRA-OF) for detection of PRRSV types 1 and 2. Among the sera, IDEXX-Se and HIPRA-Se had similar sensitivity and specificity (p>0.05); however, IDEXX-Se detected positive animals earlier than HIPRA-Se (p<0.05). FMIA-Se had the highest false-positive rates in known negative field samples (1/205 for IDEXX-Se, 5/205 for HIPRA-Se, and 37/205 for FMIA-Se; p<0.01). Serum and oral fluid samples had similar detection rates and antibody kinetics using the IDEXX tests. There was a higher detection rate in serum than oral fluid using the HIPRA assays. In this study, the nucleocapsid protein utilized as antigen in the FMIAs yielded a low specificity. IDEXX-Se had the earliest detection and similar sensitivity and specificity to the HIPRA-Se.

Fetal infections and antibody profiles in pigs naturally infected with porcine circovirus type 2 (PCV2).

The aim of this study was to describe early infections with porcine circovirus type 2 (PCV2) in naturally infected piglets and the piglets' serologic profiles. A total of 20 sows (15 PCV2-vaccinated and 5 unvaccinated) and 100 newborn piglets were studied. Colostrum and serum of the sows and serum of the presuckling piglets were obtained on the day of parturition. Milk samples were collected on day 20 postpartum. Blood samples were taken and the piglets weighed on days 1, 20, 42, 63, and 84 postpartum. Colostrum and milk were evaluated for infectious PCV2 and for PCV2 total antibody (TA), neutralizing antibody (NA), and IgA. Serum samples were evaluated for PCV2 TA, NA, IgA, IgM, and DNA. The sows had high levels of TA and NA in serum and colostrum; however, 11 and 5, respectively, of the 20 colostrum and milk samples contained infectious PCV2. In the serum, PCV2 DNA and IgM were detected in 17 and 5, respectively, of the 20 sows. Nine piglets were born with PCV2 antibodies, which indicates in utero transmission of PCV2 after the period of immunocompetence (> 70 d of gestation). On day 1 postpartum, PCV2 DNA was detected in 29 of the 100 serum samples from the piglets. There was no difference between the weights of viremic and nonviremic piglets throughout the study. In conclusion, even on farms with sows that have high PCV2 antibody titers, vertical transmission of PCV2 may occur, resulting in piglet infection.

Validation of an immunoperoxidase monolayer assay for total anti-Vaccinia virus antibody titration.

Vaccinia virus (VACV) has been associated with zoonotic exanthemic outbreaks affecting bovids and human beings, with significant public health and economic impacts. Rapid and reliable diagnostic methods are needed to detect and epidemiologically monitor antibodies to VACV. The current study describes the development of an immunoperoxidase monolayer assay (IPMA) for detection of total VACV antibodies in bovine serum. The assay was validated by comparison with a plaque reduction neutralization test (PRNT). Kappa index of agreement, diagnostic sensitivity, specificity, and accuracy of the IPMA were -1.008, 100%, 96%, and 98%, respectively, when compared with PRNT on 148 field bovine sera. Repeatability tests on 32 field-positive serum samples revealed that intraclass coefficient correlation was 0.86. In experimentally infected cattle, VACV antibodies were detectable by IPMA 4 days postinfection, which was more than 2 weeks earlier than with the PRNT, indicating that IPMA could be a more sensitive test than the latter. In 4 naturally VACV-diseased cows monitored for 13 months, IPMA could detect VACV antibodies up to 13 months, a longer time than PRNT. The IPMA is simpler to produce and perform when compared with PRNT and is time saving and suitable for large-scale surveys of VACV infection in bovine.

Orbivirus infections in collared peccaries (Tayassu tajacu) in southeastern Brazil.

We surveyed 49 free-living collared peccaries (Pecari tajacu) in Brazil for antibodies against bluetongue virus (BTV) and porcine circovirus 2 (PCV2). Antibodies against BTV were detected in 19/49 (39%) samples. All samples were negative for PCV2. The importance of antibodies to BTV in collared peccaries remains to be determined.

Serum antibodies and shedding of infectious porcine circovirus 2 into colostrum and milk of vaccinated and unvaccinated naturally infected sows.

Serum antibodies and shedding of porcine circovirus type 2 (PCV2) into lacteal secretions were examined in naturally infected sows. Total (TA) and neutralising (NA) antibodies against PCV2 were evaluated in serum and colostrum from 20 vaccinated (Vac) and 21 unvaccinated (N-vac) sows. Anti-PCV2 IgA titres and PCV2 infectious titres were determined in colostrum and milk. All sows had high TA and NA levels in serum and colostrum. Infectious PCV2 was detected in 22/41 colostrum samples (7/20 Vac and 15/21N-Vac sows) and 5/20 milk samples (1/5 Vac and 4/15N-Vac sows). Anti-PCV2 IgA was found in high levels in colostrum and varying levels in milk. Infectious PCV2 may be present in milk and colostrum of naturally infected sows, even in the presence of NA.

Perfil sorológico, viremia e eliminação do circovírus suíno tipo 2 em animais naturalmente infectados pertencentes a granjas com ou sem a síndrome da refugagem multissistêmica / Serological profile, viremia and PCV2 shedding in naturally infected pigs of herds with or without postweaning multisystemic wasting syndrome

Um estudo virológico e sorológico seccional (E1) e outro longitudinal (E2) foram realizados em granjas com (G2 e G3) e sem (G1) a síndrome de refugagem multissitêmica (SRM) no Brasil. Foram coletadas amostras de sangue, soro, swabs nasal e retal de animais de cada categoria do ciclo produtivo: porcas, leitões maternidade, creche, recria e terminação. Em E1, nas granjas G1a e G2, foram amostrados 40 animais de cada categoria. Em E2, nas granjas G1b e G3, 35 leitões na maternidade foram identificados e amostrados ao longo do ciclo produtivo. O soro foi avaliado para presença de anticorpos contra circovírus suíno tipo 2 (CVS2) e sangue e swabs para presença do ácido nucléico viral. Em E1, a categoria porcas possuía altas taxas de animais virêmicos e soropositivos, com porcentagem de porcas com títulos altos superior a G2. Em G1a a queda de imunidade passiva ocorreu entre o final da fase de creche e início da recria com aumento da eliminação viral em swabs e subsequente soroconversão. Em G2 a queda ocorreu entre a fase final da maternidade e início da creche, com diminuição da eliminação viral. Em E2, a queda da imunidade materna ocorreu entre a 1ª e 2ª coleta em G1b; e em G3, entre a 2ª e 3ª coleta. Em ambas as granjas, a queda de imunidade passiva coincidiu com o aumento da viremia e eliminação viral e a soroconversão ocorreu entre a 3ª e 4a coleta em ambas as granjas com aumento da média de título de anticorpos e declínio da viremia. Viremia e eliminação viral foram detectadas em todas as coletas realizadas; 42% dos animais amostrados em E2 foram virêmicos em todas as coletas e todas as amostras de tecido coletadas no abate foram positivas para o CVS2. Este estudo confirma a persistência da viremia mesmo em presença de altos títulos de anticorpos e que o perfil sorológico em um rebanho com e sem a presença da síndrome pode ser diferente, principalmente em relação à duração da imunidade passiva.

A virological and serological cross-sectional study (E1) and a longitudinal study (E2) were performed on herds with (G2 and G3) and without (G1) post weaning multisystemic syndrome (PMWS) in Brazil. Blood, serum, nasal and rectal swabs samples were collected of sows, farrowing piglets, nursery, growing and finishing pigs. In E1, were sampled 40 animals in each category (G1a and G2). In E2, (G1b and G3), 35 farrowing piglets were identified and sampled along the production cycle. Porcine circovirus type 2 (PCV2) antibodies were assayed. A PCR was used to detected PCV2 genome in blood and swabs. In E1, sows had high rates of viremic and seropositives animals, with percentage of sows with high antibodies titers greater than G2. Passive antibodies decline occurred between nursery and growing area with increased viral shedding in swabs and subsequent seroconversion in G1. In G2, the passive antibodies decay occurred in nursery, with a reduction in viral shedding. In E2, the decline of maternal immunity occurred between the 1st and 2nd collection in G1b, and between 2nd and 3rd collections in G3. In both herds, the decay of passive immunity coincided with increased viremia and viral shedding; and seroconversion occurred between the 3rd and 4th collection in both herds with decline of viremia. Viremia and viral shedding was detected in all samples days, 42% of animals sampled in E2 were viremic and all tissue samples collected at slaughterwere positive for PCV2. This study confirms the persistence of viremia even in the presence of high titers of antibodies and the serological profile in a herd with or without PMWS may be different, especially with regard to the passive immunity duration.

Detection and dynamics of porcine circovirus 2 shedding in semen using conventional and real-time PCR / Deteccão e dinâmica de excreção do circo vírus porcino tipo 2 no semen pelo PCR convencional e PCR em tempo real

The dynamics of porcine circovirus type 2 (PCV2) shedding in semen of naturally infected boars was studied. Semen was collected serially each 15 or 20 days during 62 days from 5 boars from a herd and from 11 boars from an artificial insemination center. All boars were positive for PCV2 DNA by nested polymerase chain reaction of raw semen in at least two sampling dates, and most of them had detectable shedding in all sampling dates. Real-time quantitative PCR was performed in 23 samples. All samples showed low amounts of PCV2 DNA, ranging from 98 to 652 PCV2 copies/mL. No differences between the frequencies of PCV2 DNA shed in semen were found considering herds and age of boars. PCV2 shedding in the semen can occur continuously or intermittently up to 60 days in naturally infected boars at 12 to 42 months old in absence of PCV2 clinical signs. These results demonstrate sporadic and long-term shedding patterns of low amounts of PCV2 DNA in semen from naturally infected boars.(AU)

A dinâmica da excreção do circovírus suíno tipo 2 (CVS2) em sêmen de machos naturalmente infectados foi estudada. Amostras de sêmen de cinco machos de um plantel e de 11 machos de um centro de inseminação artificial foram coletadas a cada 15 ou 20 dias durante 62 dias. Todos os machos testados foram positivos para a presença do DNA viral no sêmen em pelo menos duas coletas, sendo que a maioria deles eliminou o CVS2 em todas as coletas. O teste de PCR quantitativa em tempo real foi aplicado em 23 amostras. Todas as amostras tinham baixa quantidade de DNA viral, variando de 98 a 652 cópias de CVS2/ml. Não houve diferença na freqüência de eliminação do DNA viral levando em conta os plantéis e idade dos machos. A excreção do CVS2 no sêmen pode ocorrer de forma contínua ou intermitente por mais de 60 dias em machos de 12 a 42 meses de idade naturalmente infectados na ausência de sinais clínicos de CVS2. Estes resultados demonstram padrões esporádico e de longa duração de excreção viral em pequenas quantidades no sêmen de varrões naturalmente infectados.(AU)

Detection and dynamics of porcine circovirus 2 shedding in semen using conventional and real-time PCR / Deteccão e dinâmica de excreção do circo vírus porcino tipo 2 no semen pelo PCR convencional e PCR em tempo real

The dynamics of porcine circovirus type 2 (PCV2) shedding in semen of naturally infected boars was studied. Semen was collected serially each 15 or 20 days during 62 days from 5 boars from a herd and from 11 boars from an artificial insemination center. All boars were positive for PCV2 DNA by nested polymerase chain reaction of raw semen in at least two sampling dates, and most of them had detectable shedding in all sampling dates. Real-time quantitative PCR was performed in 23 samples. All samples showed low amounts of PCV2 DNA, ranging from 98 to 652 PCV2 copies/mL. No differences between the frequencies of PCV2 DNA shed in semen were found considering herds and age of boars. PCV2 shedding in the semen can occur continuously or intermittently up to 60 days in naturally infected boars at 12 to 42 months old in absence of PCV2 clinical signs. These results demonstrate sporadic and long-term shedding patterns of low amounts of PCV2 DNA in semen from naturally infected boars.

A dinâmica da excreção do circovírus suíno tipo 2 (CVS2) em sêmen de machos naturalmente infectados foi estudada. Amostras de sêmen de cinco machos de um plantel e de 11 machos de um centro de inseminação artificial foram coletadas a cada 15 ou 20 dias durante 62 dias. Todos os machos testados foram positivos para a presença do DNA viral no sêmen em pelo menos duas coletas, sendo que a maioria deles eliminou o CVS2 em todas as coletas. O teste de PCR quantitativa em tempo real foi aplicado em 23 amostras. Todas as amostras tinham baixa quantidade de DNA viral, variando de 98 a 652 cópias de CVS2/ml. Não houve diferença na freqüência de eliminação do DNA viral levando em conta os plantéis e idade dos machos. A excreção do CVS2 no sêmen pode ocorrer de forma contínua ou intermitente por mais de 60 dias em machos de 12 a 42 meses de idade naturalmente infectados na ausência de sinais clínicos de CVS2. Estes resultados demonstram padrões esporádico e de longa duração de excreção viral em pequenas quantidades no sêmen de varrões naturalmente infectados.

Distribution of antibodies against porcine circovirus type-2 (PCV2) in single site and multi-site farrow-to-finish farms in Brazil.

A comparative serologic study was performed in seven single site (SS) farrow-to-finish farms and four multi-site (MS) farrow-to-finish farms, with or without post-weaning multisystemic wasting syndrome (PMWS). In each farm, 30 blood samples were collected for each category of the production cycle: sows, farrowing crate, nursery, grower pigs, and finishing pigs. Sera were evaluated for the presence of antibodies to porcine circovirus type-2 (PCV2) via immunoperoxidase monolayer assay. Serologic profiles for PCV2 were different between SS and MS farms. Seroconversion following the decline in maternal antibodies occurred at a later stage on SS farms (grower pigs) than MS farms (nursery pigs). MS farms tended to have lower antibody titers than SS farms in the categories of sow, piglet, and nursery, while higher antibody titers were found in grower pigs. Characterization of serologic profiles for different farms may provide important information for the adoption of vaccination programs.