Genetic characterization of bovine herpesvirus 4 (BoHV-4) isolates from Argentine cattle suggests a complex evolutionary scenario.

Bovine herpevsirus 4 (BoHV-4) is a gammaherpesvirus that has been associated with different clinical conditions in cattle. In Argentina, BoHV-4 was detected in diverse bovine samples. The aim of this study was to analyze the genetic relationship of 48 field BoHV-4 strains isolated from cattle in Argentina. According to thymidine kinase (tk) gene sequences, BoHV-4 isolates belong to genotypes 1, 2 and 3. Phylogenetic analyses confirmed the presence of the three previously described viral genotypes. However, some of the studied isolates presented conflicting phylogenetic signals between the studied markers. This suggests a complex evolutionary background, that is a history of recombination, incomplete lineage sorting (deep coalescence) or a combination of these, which requires further study. These potential events make difficult the diagnosis of BoHV-4 from clinical samples of cattle and may pose a significant problem for the control of the virus in the herds.

Molecular Epidemiology of Rotavirus A in Calves: Evolutionary Analysis of a Bovine G8P[11] Strain and Spatio-Temporal Dynamics of G6 Lineages in the Americas.

Rotavirus A (RVA) causes diarrhea in calves and frequently possesses the G6 and P[5]/P[11] genotypes, whereas G8 is less common. We aimed to compare RVA infections and G/P genotypes in beef and dairy calves from major livestock regions of Argentina, elucidate the evolutionary origin of a G8 strain and analyze the G8 lineages, infer the phylogenetic relationship of RVA field strains, and investigate the evolution and spatio-temporal dynamics of the main G6 lineages in American countries. Fecal samples (n = 422) from diarrheic (beef, 104; dairy, 137) and non-diarrheic (beef, 78; dairy, 103) calves were analyzed by ELISA and semi-nested multiplex RT-PCR. Sequencing, phylogenetic, phylodynamic, and phylogeographic analyses were performed. RVA infections were more frequent in beef (22.0%) than in dairy (14.2%) calves. Prevalent genotypes and G6 lineages were G6(IV)P[5] in beef (90.9%) and G6(III)P[11] (41.2%) or mixed genotypes (23.5%) in dairy calves. The only G8 strain was phylogenetically related to bovine and artiodactyl bovine-like strains. Re-analyses inside the G8 genotype identified G8(I) to G8(VIII) lineages. Of all G6 strains characterized, the G6(IV)P[5](I) strains from "Cuenca del Salado" (Argentina) and Uruguay clustered together. According to farm location, a clustering pattern for G6(IV)P[5] strains of beef farms was observed. Both G6 lineage strains together revealed an evolutionary rate of 1.24 × 10-3 substitutions/site/year, and the time to the most recent common ancestor was dated in 1853. The most probable ancestral locations were Argentina in 1981 for G6(III) strains and the USA in 1940 for G6(IV) strains. The highest migration rates for both G6 lineages together were from Argentina to Brazil and Uruguay. Altogether, the epidemiology, genetic diversity, and phylogeny of RVA in calves can differ according to the production system and farm location. We provide novel knowledge about the evolutionary origin of a bovine G8P[11] strain. Finally, bovine G6 strains from American countries would have originated in the USA nearly a century before its first description.

Parasitemia and Associated Immune Response in Pregnant and Non-Pregnant Beef Cows Naturally Infected With Neospora caninum.

The aim of this longitudinal study was to characterize the parasitemia of Neospora caninum and the associated immunological parameters in naturally infected beef cows for 10 months. The following groups were established: Neospora caninum seropositive pregnant cows (+Preg, n = 7), seropositive non-pregnant cows (+Npreg, n = 7), seronegative pregnant cows (-Preg, n = 4), and seronegative non-pregnant cows (-Npreg, n = 4). Several samples were obtained for absolute and relative leukocyte counting, cytokines IL-10, IL-12, α-TNF, and γ-IFN quantification, specific IgG, IgG1, and IgG2 and avidity and N. caninum DNA molecular detection and quantification. The +Preg group had a higher frequency and concentration of N. caninum DNA in PBMC in the last third of pregnancy compared to +Npreg (p <0.05), with 22 and 8% of detection, respectively. Parasitemia correlated positively with IgG titers and negatively with IgG1/IgG2 ratio (p <0.05). On day 222 of the assay, the +Preg group had the lowest total leukocyte counting (p <0.05). The +Preg group had a higher concentration of IgG and higher avidity in the last third of gestation compared to +Npreg (p <0.05). Avidity correlated with total IgG and IgG2 (p <0.05). All +Preg cows gave birth to clinically healthy but seropositive calves before colostrum intake, therefore, the congenital transmission was 100% efficient. Only a complete N. caninum genotype from a placenta and a partial genotype from cow #3 of the group +Preg were achieved by multilocus microsatellite analysis. Overall, N. caninum parasitemia is frequent in seropositive beef cows during the last third of gestation. This correlates with higher antibody levels and a decrease in total leukocyte counting. The precise timing of the parasitemia may be used for diagnosis purposes and/or for design strategies to avoid vertical transmission. Further studies are needed to identify the immune molecular mechanisms that favor parasitemia during gestation in chronically infected cattle.

Genomic diversity and phylodynamic of bovine viral diarrhea virus in Argentina.

Bovine viral diarrhea virus (BVDV) is an important pathogen of ruminants worldwide and is characterized by high genetic diversity and a wide range of clinical presentations. In Argentina, several studies have evaluated the genetic diversity of BVDV but no phylodynamic study has been published yet. In this study, a comprehensive compilation and update of Argentinean BVDV sequences were performed, and the evolutionary history of BVDV was characterized by phylodynamic analyses based on the 5´UTR. Although BVDV-1b and BVDV-1a were the most frequent subtypes, novel subtypes for Argentina, 1e and 1i, were identified. The phylodynamic analysis suggested that BVDV started its diversification in the mid-1650s with an exponential increase in viral diversity since the late 1990s, possibly related to the livestock expansion and intensification in the country. Evolutionary rate in the 5´UTR was faster for BVDV-1a than for BVDV-1b, and both subtypes presented an endemic nature according to the demographic reconstructions. The current study contributes to clarify the evolutionary history of BVDV in the main cattle region of the country and provides useful information about the epidemiology and future development of diagnostic and control tools in Argentina.

Seroepidemiology of beef and dairy herds and fetal study of Neospora caninum in Argentina.

The purpose of the present work was to study the epidemiology of Neospora caninum in beef and dairy herds in the Humid Pampas of Argentina. The seroprevalence of N. caninum was evaluated in 2414 serum samples of cows from beef and dairy farms. An indirect fluorescent antibody test (IFAT) was used to determine specific antibodies. The sera was screened at a dilution >or=1:200 and >or=1:600 in cows with reproductive disease antecedents and without them, respectively. Cows without history of reproductive diseases from nine beef and fifteen dairy farms were grouped according to the percentage (> or or

Safety and efficacy of an E2 glycoprotein subunit vaccine produced in mammalian cells to prevent experimental infection with bovine viral diarrhoea virus in cattle.

Bovine viral diarrhea (BVD) infection caused by bovine viral diarrhea virus (BVDV), a Pestivirus of the Flaviviridae family, is an important cause of morbidity, mortality and economical losses in cattle worldwide. E2 protein is the major glycoprotein of BVDV envelope and the main target for neutralising antibodies (NAbs). Different studies on protection against BVDV infection have focused on E2, supporting its putative use in subunit vaccines. A truncated version of type 1a BVDV E2 (tE2) expressed in mammalian cells was used to formulate an experimental oleous monovalent vaccine. Immunogenicity was studied through immunisation of guinea pigs and followed by trials in cattle. Calves of 8-12 months were vaccinated, twice with a 4 week interval, with either a tE2 subunit vaccine (n = 8), a whole virus inactivated vaccine (n = 8) or left untreated as negative control group (n = 8). Four weeks after the last immunisation the animals were experimentally challenged intranasally with a non-cythopathic BVDV strain. Following challenge, BVDV was isolated from all unvaccinated animals, while 6 out of 8 animals vaccinated with tE2 showed complete virological protection indicating that the tE2 vaccine presented a similar performance to a satisfactory whole virus inactivated vaccine.

Occurrence of bovine herpesvirus type 4 DNA in Argentinean Holstein cattle from Santiago del Estero, Argentina / Ocorrência de DNA de herpesvírus bovino tipo 4 em gado Holstein argentino de Santiago del stero, Argentina

and from cattle with a variety of clinical signs. The pathogenic role of BoHV-4 remains unclear and it is unknown whether the virus acts as a primary pathogen or whether it facilitates secondary infections After natural or experimental infections, BoHV-4 can establish latency, mainly in cells of the monocyte/macrophage linage. Latent virus can be reactivated after glucocorticoid treatment or by stress factors. In 2007, BoHV-4 was isolated for the first time in Argentina, from samples of bovine abortions. In the present study, we used viral isolation, nested PCR and restriction endonuclease analysis (REA) to investigate the presence of BoHV-4 in bovine leukocytes from a single herd of dairy cattle with reproductive problems. In this work, we demonstrated that BoHV-4 genome is present in the leukocytes of a high proportion (63.4%) of animals, probably in a latent or persistent state. BoHV-4 was isolated from one out of eleven peripheral blood leukocyte (PBL) samples. By REA we demonstrated the existence of genomic variation among the strains circulating in this particular herd. Furthermore, all PBL samples evaluated in this study differed from the American prototype strain, DN 599. Overall, this work demonstrated that BoHV-4 is present in the leukocyte fraction of dairy cattle and that viral strains present in this herd are genetically divergent. Although BoHV-4 was detected in a herd with a background of reproductive disorders, it is not possible to conclude that the virus is the primary responsible for these conditions.

O herpesvírus bovino tipo 4 (BoHV-4) é um gama-herpesvírus que foi isolado de animais aparentemente saudáveis e de gado com uma variedade de sinais clínicos. O papel patogênico do BoHV-4 ainda não está claro e não se sabe se o vírus age como um patógeno primário ou se facilita infecções secundárias. Depois de infecções naturais ou experimentais, BoHV-4 pode estabelecer latência, principalmente nas células dos linhagens de monócitos/macrófagos. O vírus latente pode ser reativado após o uso de glicocorticóides ou por fatores de estresse. Em 2007, o BoHV-4 foi isolado pela primeira vez na Argentina, a partir de amostras de abortos bovinos. No presente estudo, utilizou-se o isolamento viral, nested PCR e análise com endonucleases de restrição (REA) para investigar a presença de BoHV4 em leucócitos de bovinos provenientes de um único rebanho de gado leiteiro com problemas reprodutivos. Neste trabalho, demonstramos que o genoma do BoHV-4 está presente nos leucócitos em uma elevada proporção (63,4%) dos animais, provavelmente em um estado latente ou persistente. BoHV-4 foi isolado de uma de cada onze amostras de leucócitos no sangue periférico (PBL). Por REA nós demonstramos a existência de variações genômicas entre as estirpes circulantes deste rebanho particular. Além disso, todas as amostras de PBL avaliados neste estudo diferiram da estirpe protótipo Americano, DN 599. Em geral, este estudo demonstrou que o BoHV-4 está presente na fração leucocitária do gado leiteiro e que as estirpes virais presentes neste rebanho são geneticamente divergentes. Embora que BoHV-4 foi detectado em um rebanho com história de distúrbios reprodutivos, não é possível concluir que o vírus é o principal responsável por estas condições.