Víctor J Vera

Detection and molecular characterization of porcine circovirus type 2 from piglets with Porcine Circovirus Associated Diseases in Colombia

BackgroundThe porcine circovirus-associated disease (PCVAD) has been known since 1991 in Canada, but the first outbreak of PCVAD in Colombia was reported in 2007. In order to understand the molecular epidemiology of the disease and to establish the origin of the virus in the country, the study presented here intended to evaluate the presence of PCV2-associated systemic infection in piglets from different geographical regions over a period of 9-years (2002 -2010). The analysis included samples collected before, during and after outbreaks of PCVAD in pigs from Colombia. The PCV2 ORF2 from the positive samples was sequenced and used to determine the genotypes of the strains and to study the dynamic of these genotypes throughout the time.ResultsPCV2 DNA was detected in cases related to PCV2-associated systemic infection as well as in healthy pigs with a presumable persistent infection. The analysis of the ORF2 nucleotide full length sequence of twenty-three strains allowed to divide them into two groups: PCV2a and PCV2b. At the amino acid level the main variations in the sequence of the capsid protein were found in regions located within the immunoreactive areas.ConclusionsThe results of this study demonstrated for the first time, that the two subgroups: PCV2a and PCV2b have been circulating in swine from Colombia. In addition, the study showed that genotype PCV2b is present in Colombian pigs suffering from both clinical and presumable persistent infection and that the PCV2b genotype was present in the Colombian pig population even before recognition of the disease in the country and it became predominant through time.

An inactivated vaccine from a field strain of bovine herpesvirus-1 (BoHV-1) has high antigenic mass and induces strong efficacy in a rabbit model

Bovine Herpesvirus-1 (BoHV-1) is a DNA virus belonging to the family Herpesviridae, subfamily Alfaherpesvirinae; it is a worldwide pathogen, causing serious economic losses in livestock. In Colombia there have been multiple isolates of BoHV-1 that have been subjected to molecular characterization, classifying most of the country isolates as BoHV-1.1. In the present study we developed and evaluated an ethyleneimine binary inactivated isolate from the native BoHV-1 strain (Córdoba-2) in a rabbit model of vaccination and infection. The vaccine was evaluated in two phases, one of immunogenicity with vaccination and a booster after 21 days, and an evaluation phase of protection against challenge with a highly virulent reference strain. The results demonstrate optimum serum-conversion, with protective neutralizing antibody titers 28 days post vaccination and optimal protection against challenge with the reference strain with decreased clinical signs of infection, protection against the onset of fever and decrease of virus excretion post challenge. In conclusion, our results show the enormous potential that an immunogenic inactivated vaccine has produced from the native BoHV-1.1 strain, which produces a high antigen mass to the vaccine to induce optimal immunity and protection, and it is a strong candidate for evaluation and possible future use in different cattle populations.

Molecular and in vitro characterization of field isolates of bovine herpesvirus-1

Bovine Herpesvirus-1 (BoHV-1) is distributed worldwide and is a major pathogen in cattle, being the causal agent of a variety of clinical syndromes. The aim of this study was to isolate and to characterize (molecular and biological characterization) BoHV-1 from 29 immunosuppressed animals. It was possible to obtain 18 isolates, each from a different animal, such as from the respiratory and reproductive tracts. In some cases the cytopathic effect was visible 12 hours post-inoculation, and became characteristic after 36–48 hours. Biological characteristics were evaluated and compared with Iowa and Colorado-1 reference strains, and differences were found in plaque size, virus titer measured by TCID50 and PFU/mL, and one step virus curves. These results showed that some isolates had a highly virulent-like behavior in vitro, compared to the reference strains, with shorter eclipse periods, faster release of virus into the supernatants, and higher burst size and viral titer. There were no differences in glycoprotein expression of BoHV-1 isolates, measured by Western blot on monolayers. Moreover, using restriction endonucleases analysis, most of the viruses were confirmed as BoHV-1.1 and just one of them was confirmed as BoHV-1.2a subtype. These findings suggest that some wild-type BoHV-1 isolates could be useful as seeds to develop new monovalent vaccines.

Evaluación de la prueba ELISA usando una cepa de campo como antígeno, para detectar anticuerpos contra el virus de la Rinotraqueitis Bovina Infecciosa

Evaluation of ELISA test use of field strain (antigen) to detect antibodies against Infectious Bovine Rhinotracheitis virus. The following study set up an enzymatic immune test (ELISA) using viral particles broke up of field strain of IBR virus; it showed a high sensibility and specificity and low rate of false negatives and positives. Positive and negative bovine serum which ELISA technique was normalized, were analyzed by seroneutralization to determine anti IBR antibodies; It was collected positive and negative serum with titles 1:4 to 1:128 and was considered dilution of bovine serum 1:50 as optimal dilution to ELISA technique. On the other hand, coefficient of variation BR was used to analyze the rehearsing of absorbance obtained by positive and negative serum. The results obtained were less than 20%, which indicated an appropriate

Cultivos celulares como alternativa para el aislamiento y la producción de biológicos contra el Virus de Influenza

Influenza Virus has been recognized as an important pathogen in human and animal populations causing many respiratory diseases. Vaccine production and isolation of human and animal influenza viruses are made mainly in chicken embryo eggs, being the conventional method used for decades, however, several issues have been found for vaccine manufacture related with low efficiency of processes due to limited capacity of production (sometimes requiring one or two eggs to obtain a vaccine dose) and time spending that leads to decrease in the ability for fast vaccine production processes in a pandemic situation. The use of continuous cell lines for viral vaccine manufacture rises as a feasible choice offering several advantages including the opportunity to use fully characterized and standardized cells; in addition, cell-culture-derived vaccines don?t require further planning and vaccines can be produced rapidly. The aim of this paper is to know different alternatives employed in culture and isolation of influenza viruses, emphasizing in the use of cell culture as a substrate for isolation and manufacture of vaccines for use in humans and animals.

Aspectos generales del virus de la encefalitis equina venezolana (VEEV)

Resumen es: El virus de la Encefalitis Equina Venezolana (VEEV) pertenece a los Alphavirus. Es transmitido por mosquitos y es una enfermedad emergente en equinos, hu...