Molecular characterization of infectious bursal disease virus (IBDV) isolated in Argentina indicates a regional lineage.

In Argentina, classical vaccines are used to control infectious bursal disease virus (IBDV); however, outbreaks of IBDV are frequently observed. This could be due to failures in the vaccination programs or to the emergence of new strains, which would be able to break through the protection given by vaccines. Hence, genetic characterization of the viruses responsible for the outbreaks that occurred in recent years is crucial for the evaluation of the control programs and the understanding of the epidemiology and evolution of IBDV. In this study, we characterized 51 field samples collected in Argentina (previously identified as IBDV positive) through the analysis of previously identified apomorphic sequences. Phylogenetic analysis of regVP2 showed that 42 samples formed a unique cluster (Argentinean lineage), seven samples were typical classical strains (one of them was a vaccine strain), and two belonged to the very virulent lineage (vvIBDV). Interestingly, when the analysis was performed on the regVP1 sequences, the field samples segregated similarly to regVP2; thus, we observed no evidence of a reassortment event in the Argentinean samples. Amino acid sequence analysis of regVP2 showed a particular pattern of residues in the Argentinean lineage, particularly the presence of T272, P289 and F296, which had not been reported before as signature sequences for any IBDV phenotype. Notably, the residue S254, characteristic of the antigenic variant, was not present in any of the Argentinean samples.

Molecular characterization of chicken infectious anemia virus circulating in Argentina during 2007.

Chicken infectious anemia virus (CAV) is a worldwide-distributed infectious agent that affects commercial poultry. Although this agent was first detected in Argentina in 1994, no further studies on CAV in this country were reported after that. The recent increased occurrence of clinical cases of immunosuppression that could be caused by CAV has prompted this study. Our results confirmed that CAV is still circulating in commercial flocks in Argentina. Phylogenetic analysis focusing on the VP1 nucleotide sequence showed that all Argentinean isolates grouped together in a cluster, sharing a high similarity (> 97%) with genotype B reference strains. However, Argentinean isolates were distantly related to other strains commonly used for vaccination in this country, such as Del-Ros and Cux-1. Sequence analysis of predicted VP1 peptides showed that most of the Argentinean isolates have a glutamine residue at positions 139 and 144, suggesting that these isolates might have a reduced spread in cell culture compared with Cux-1. In addition, a particular amino acid substitution at position 290 is present in all studied Argentinean isolates, as well as in several VP1 sequences from Malaysia, Australia, and Japan isolates. Our results indicate that it is possible to typify CAV strains by comparison of VPI nucleotide sequences alone because the same tree topology was obtained when using the whole genome sequence. The molecular analysis of native strains sheds light into the epidemiology of CAV in Argentinean flocks. In addition, this analysis could be considered in future control strategies focused not only on breeders but on broilers and layer flocks.

First report of BVDV circulation in sheep in Argentina.

Pestiviruses are capable of infecting a wide range of animals within the order Artyodactila. Currently, the genus Pestivirus includes Bovine Viral Diarrhea Virus 1 (BVDV-1) and 2 (BVDV-2), Border Disease Virus (BDV), and Classical Swine Fever Virus (CSFV). BVDV-1, BVDV-2 and BDV are able to cross species barrier to infect a wide range of hosts, whereas CSFV is restricted to domestic pigs and wild boars. In Argentina, 70% of cattle are seropositive to BVDV. Although there were some serological studies in llamas, alpacas and buffaloes, no reports existed about the circulation of BVDV in sheep in Argentina. Based on these, 54 blood samples of healthy ovines were analysed by serology. The results showed that 46.3% of the analysed sheep were seropositive to BVDV-1, 13% to BVDV-2 and 20.4% for both BVDV-1 and BVDV-2. The molecular analysis confirmed the presence of BVDV-1a in some samples.

Detection of bovine viral diarrhoea virus (BVDV) nucleic acid and antigen in different organs of water buffaloes (Bubalus bubalis).

Bovine viral diarrhoea virus (BVDV) is a pestivirus that infects mainly bovine cattle. Nevertheless, there are several reports about infections in other members of the Artiodactyla order including serological studies, that indicate infection of BVDV in buffaloes. The aim of this article is to study the presence of BVDV in three young water buffaloes, displaying nonspecific clinical signs, compatible with the BVDV infection. Both immunohistochemistry and RT-PCR confirmed the presence of BVDV in the animals. The sequence analysis on RT-PCR amplicons revealed high identity with reference strains of genotypes 1a and 1b. Although BVDV was unequivocally identified in the sick animals, it has not been proved it is responsible for the clinical signs. Further studies are needed to clarify the pathogenic role of BVDV infection in this animal species, and the role of buffaloes in the epidemiology of BVDV infection.

[Equine herpesvirus 2: A study on the relation between viral excretion and respiratory disease in thoroughbred horses]. / Herpesvirus equino 2: estudio de la relación entre excreción viral y enfermedad respiratoria en equinos deportivos pura sangre de carrera.

Equine herpesvirus 2 (EHV-2) was isolated from healthy animals; therefore, the association between EHV-2 infection and respiratory disease raises the question of the role of this agent in this pathology. To date, there are no reports that relate viral excretion to health, this study then analysed 153 nasal swabs from horses in different age groups (older and younger than 1 year old) and state of health (clinically healthy and with respiratory symptoms). Results showed that the percentage of horses with viral excretion was higher within the clinically healthy group, being significative (p < 0.05) in the younger than 1 year old group, whereas the percentage of animals with respiratory symptoms did not show significant differences (p > 0.05) between age groups.

Modulation by colostrum-acquired maternal antibodies of systemic and mucosal antibody responses to rotavirus in calves experimentally challenged with bovine rotavirus.

The effect of colostral maternal antibodies (Abs), acquired via colostrum, on passive protection and development of systemic and mucosal immune responses against rotavirus was evaluated in neonatal calves. Colostrum-deprived (CD) calves, or calves receiving one dose of pooled control colostrum (CC) or immune colostrum (IC), containing an IgG1 titer to bovine rotavirus (BRV) of 1:16,384 or 1:262,144, respectively, were orally inoculated with 105.5 FFU of IND (P[5]G6) BRV at 2 days of age. Calves were monitored daily for diarrhea, virus shedding and anti-BRV Abs in feces by ELISA. Anti-rotavirus Ab titers in serum were evaluated weekly by isotype-specific ELISA and virus neutralization (VN). At 21 days post-inoculation (dpi), all animals were euthanized and the number of anti-BRV antibody secreting cells (ASC) in intestinal and systemic lymphoid tissues were evaluated by ELISPOT. After colostrum intake, IC calves had significantly higher IgG1 serum titers (GMT=28,526) than CC (GMT=1195) or CD calves (GMT<4). After BRV inoculation, all animals became infected with a mean duration of virus shedding between 6 and 10 days. However, IC calves had significantly fewer days of diarrhea (0.8 days) compared to CD and CC calves (11 and 7 days, respectively). In both groups receiving colostrum there was a delay in the onset of diarrhea and virus shedding associated with IgG1 in feces. In serum and feces, CD and CC calves had peak anti-BRV IgM titers at 7 dpi, but IgA and IgG1 responses were significantly lower in CC calves. Antibody titers detected in serum and feces were associated with circulation of ASC of the same isotype in blood. The IC calves had only an IgM response in feces. At 21 dpi, anti-BRV ASC responses were observed in all analyzed tissues of the three groups, except bone marrow. The intestine was the main site of ASC response against BRV and highest IgA ASC numbers. There was an inverse relationship between passive IgG1 titers and magnitude of ASC responses, with fewer IgG1 ASC in CC calves and significantly lower ASC numbers of all isotypes in IC calves. Thus, passive anti-BRV IgG1 negatively affects active immune responses in a dose-dependent manner. In ileal Peyer's patches, IgM ASC predominated in calves receiving colostrum; IgG1 ASC predominated in CD calves. The presence in IC calves of IgG1 in feces in the absence of an IgG1 ASC response is consistent with the transfer of serum IgG1 back into the gut contributing to the protection of the intestinal mucosa.

Antiviral activity of an acidic polysaccharides fraction extracted from Cedrela tubiflora leaves.

An acidic polysaccharides fraction (APS) obtained from Cedrela tubiflora leaves was tested for antiviral activity. This fraction inhibited the replication of HSV-2 and VSV, while the replication of poliovirus was not affected. APS was not virucidal, but no cytotoxicity was present in the different concentrations of APS assayed.