Development and evaluation of a replicon particle vaccine expressing the E2 glycoprotein of bovine viral diarrhea virus (BVDV) in cattle

Background: Bovine viral diarrhea virus is one of the most significant and costly viral pathogens of cattle worldwide. Alphavirus-derived replicon particles have been shown to be safe and highly effective vaccine vectors against a variety of human and veterinary pathogens. Replicon particles are non-propagating, DIVA compatible, and can induce both humoral and cell mediated immune responses. This is the first experiment to demonstrate that Alphavirus-based replicon particles can be utilized in a standard prime/boost vaccination strategy in calves against a commercially significant bovine pathogen. Findings: Replicon particles that express bovine viral diarrhea virus sub-genotype 1b E2 glycoprotein were generated and expression was confirmed in vitro using polyclonal and monoclonal antibodies specific to E2. Vaccine made from particles was generated in Vero cells and administered to BVDV free calves in a prime/boost regimen at two dosage levels. Vaccination resulted in neutralizing antibody titers that cross-neutralized both type 1 and type 2 BVD genotypes following booster vaccination. Additionally, high dose vaccine administration demonstrated some protection from clinical disease and significantly reduced the degree of leukopenia caused by viral infection. Conclusions: Replicon particle vaccines administered in a prime/boost regimen expressing BVDV E2 glycoprotein can induce cross-neutralizing titers, reduce leukopenia post challenge, and mitigate clinical disease in calves. This strategy holds promise for a safe and effective vaccine to BVDV

Determination of presence of Tritrichomonas foetus in uterine lavages from cows with reproductive problems Determinação da presença de Tritrichomonas foetus em lavados uterinos de vacas com problemas reprodutivos

The aim of this study was to determine the presence of Tritrichomonasfoetus in two dairy herds on the Altiplano Cundiboyacense. Twenty-one low-volume uterine lavages from cows with a history of reproductive problems in two dairy herds located in the municipality of Sibaté (Cundinamarca) and Ventaquemada (Boyacá) were evaluated. In the first herd, 10 cows were sampled and in the second, 11 cows, based on three inclusion criteria. The uterine lavages were obtained through infusion of physiological saline solution into the uterine body. The samples were centrifuged and seeded in Tritrichomonas basal medium for 10-15 days at 37 ºC. The protozoa were evaluated on the day of sampling and 10 and 15 days after incubation by means of direct viewing under a dark-field microscope. Positive samples were stained with Wright and Lugol to identify the morphological characteristics. This study showed that T. foetus was present in 61.8% of the animals sampled. The determination that T. foetus was present in 61.8% of the samples analyzed is a significant finding given that in the herds evaluated, this agent had not previously been diagnosed.<br>O objetivo do presente estudo, foi determinar a presença de Tritrichomonas foetus em dois rebanhos leiteiros no Altiplano Cundiboyacense. De vacas com um histórico de problemas reprodutivos, foram avaliados 21 lavados uterinos de pequeno volume, em dois rebanhos leiteiros localizados nos municípios de Sibaté (Cundinamarca) e Ventaquemada (Boyacá). No primeiro rebanho, 10 vacas foram amostradas e no segundo 11, baseado em três critérios de inclusão. Os lavados uterinos foram obtidos mediante infusão de solução salina fisiológica no corpo do útero. As amostras foram centrifugadas e semeadas em meio de cultura básico para Tritrichomonas por 10-15 dias a 37 ºC. Os protozoários foram avaliados no dia da colheita de amostras e 10 e 15 dias após incubação por meio de visualização direta sob um microscópio de campo escuro. As amostras positivas foram coradas com Wright e Lugol para identificar as características morfológicas. Este estudo mostrou que T. foetus estava presente em 61,8% dos animais amostrados. A determinação de que T. foetus estava presente em 61,8% das amostras analisadas é um achado significativo, dado que nos rebanhos avaliados, esse agente não tinha sido previamente diagnosticado

Greater numbers of nucleotide substitutions are introduced into the genomic RNA of bovine viral diarrhea virus during acute infections of pregnant cattle than of non-pregnant cattle

<p>Abstract</p> <p>Background</p> <p>Bovine viral diarrhea virus (BVDV) strains circulating in livestock herds show significant sequence variation. Conventional wisdom states that most sequence variation arises during acute infections in response to immune or other environmental pressures. A recent study showed that more nucleotide changes were introduced into the BVDV genomic RNA during the establishment of a single fetal persistent infection than following a series of acute infections of naïve cattle. However, it was not known if nucleotide changes were introduce when the virus crossed the placenta and infected the fetus or during the acute infection of the dam.</p> <p>Methods</p> <p>The sequence of the open reading frame (ORF) from viruses isolated from four acutely infected pregnant heifers following exposure to persistently infected (PI) calves was compared to the sequences of the virus from the progenitor PI calf and the virus from the resulting progeny PI calf to determine when genetic change was introduced. This was compared to genetic change found in viruses isolated from a pregnant PI cow and its PI calf, and in three viruses isolated from acutely infected, non-pregnant cattle exposed to PI calves.</p> <p>Results</p> <p>Most genetic changes previously identified between the progenitor and progeny PI viruses were in place in the acute phase viruses isolated from the dams six days post-exposure to the progenitor PI calf. Additionally, each progeny PI virus had two to three unique nucleotide substitutions that were introduced in crossing the placenta and infection of the fetus. The nucleotide sequence of two acute phase viruses isolated from steers exposed to PI calves revealed that six and seven nucleotide changes were introduced during the acute infection. The sequence of the BVDV-2 virus isolated from an acute infection of a PI calf (BVDV-1a) co-housed with a BVDV-2 PI calf had ten nucleotides that were different from the progenitor PI virus. Finally, twenty nucleotide changes were identified in the PI virus of a calf born to a PI dam.</p> <p>Conclusions</p> <p>These results demonstrate that nucleotide changes are introduced into the BVDV infecting pregnant cattle at rates of 2.3 to 8 fold higher then during the acute infection of non-pregnant animals.</p