RT-PCR for detection of bovine parainfluenza virus type 3 (bPIV-3)

The RT-PCR technique has been frequentely used for detection of the human parainfluenza virus type 3 (hPIV-3) but the literature is scarce in relation to the bovine parainfluenza virus type 3 (bPIV-3). The aim of this study was to describe a reverse transcriptase polymerase chain reaction (RT-PCR) for detection of bovine parainfluenza virus type 3 (bPIV-3) using degenerate oligonucleotides targeting a conserved region of hemagglutinin-neuraminidase (HN) gene. Reference strain SF-4 and three different brazilian bPIV-3 isolates, besides five viral strains from different sources, were included in this study. Viruses were cultured in MDBK cells under standard conditions. Hemagglutination (HA) test was used for viral titration and a direct immunofluorescence test (DFAT) for isolate screening. In RT-PCR all bPIV-3 isolates showed amplification of an expected 1009 bp fragment of HN gene, as oposed to non PIV-3 viral samples where no amplification was detected. Using SF-4 as positive control, sensitivity of 95 pg cDNA wasachieved. In spite of the low number of bPIV-3 isolates tested, the results obtained in this study point out the potential use of this technique for detection of bPIV-3 in bovine clinical specimens

ISCOM-like nanoparticles formulated with Quillaja brasiliensis Saponins are promising adjuvants for seasonal influenza vaccines

Vaccination is the most effective public health intervention to prevent influenza infections, which are responsible for an important burden of respiratory illnesses and deaths each year. Currently, licensed influenza vaccines are mostly split inactivated, although in order to achieve higher efficacy rates, some influenza vaccines contain adjuvants. Although split-inactivated vaccines induce mostly humoral responses, tailoring mucosal and cellular immune responses is crucial for preventing influenza infections. Quillaja brasiliensis saponin-based adjuvants, including ISCOM-like nanoparticles formulated with the QB-90 saponin fraction (IQB90), have been studied in preclinical models for more than a decade and have been demonstrated to induce strong humoral and cellular immune responses towards several viral antigens. Herein, we demonstrate that a split-inactivated IQB90 adjuvanted influenza vaccine triggered a protective immune response, stronger than that induced by a commercial unadjuvanted vaccine, when applied either by the subcutaneous or the intranasal route. Moreover, we reveal that this novel adjuvant confers up to a ten-fold dose-sparing effect, which could be crucial for pandemic preparedness. Last but not least, we assessed the role of caspase-1/11 in the generation of the immune response triggered by the IQB90 adjuvanted influenza vaccine in a mouse model and found that the cellular-mediated immune response triggered by the IQB90-Flu relies, at least in part, on a mechanism involving the casp-1/11 pathway but not the humoral response elicited by this formulation

Estudo da atividade antiherpética de extratos vegetais

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Could phylogenetic analysis be used for feline Leukemia Virus (FeLV) classification?

The surface envelope (SU) protein determines the cell tropism and consequently the pathogenesis of the feline leukemia virus (FeLV) in felids. Recombination of exogenous FeLV (exFeLV) with endogenous retroviruses (enFeLV) allows the emergence of more pathogenic variants. Currently, phenotypic testing through interference assays is the only method to distinguish among subgroups—namely, FeLV-A, -B, -C, -E, and -T. This study proposes a new method for FeLV classification based on molecular analysis of the SU gene. A total of 404 publicly available SU sequences were used to reconstruct a maximum likelihood tree. However, only 63 of these sequences had available information about phenotypic tests or subgroup assignments. Two major clusters were observed: (a) clade FeLV-A, which includes FeLV-A, FeLV-C, FeLV-E, and FeLV-T sequences, and (b) clade enFeLV, which includes FeLV-B and enFeLV strains. We found that FeLV-B, FeLV-C, FeLV-E, and FeLV-T SU sequences share similarities to FeLV-A viruses and most likely arose independently through mutation or recombination from this strain. FeLV-B and FeLV-C arose from recombination between FeLV-A and enFeLV viruses, whereas FeLV-T is a monophyletic subgroup that has probably originated from FeLV-A through combined events of deletions and insertions. Unfortunately, this study could not identify polymorphisms that are specifically linked to the FeLV-E subgroup. We propose that phylogenetic and recombination analysis together can explain the current phenotypic classification of FeLV viruses

Otimização da imunofluorescência direta para diagnóstico de raiva

O diagnóstico laboratorial da raiva utiliza uma metodologia padronizada, baseada essencialmente no método de imunofluorescência direta, ou “direct fluorescent antibody test” (DFAT). No presente estudo foram reavaliadas algumas variáveis do DFAT, incluindo a duração do tempo de fixação das lâminas com impressões de tecido nervoso, duração das incubações de pré-adsorção do conjugado com as suspensões de tecido nervoso de camundongos infectados (IMB) ou não infectados (NMB) e a duração do período de incubação destas misturas sobre as lâminas com as impressões fixadas. A combinação que proporcionou maior eficácia à DFAT foi obtida com a fixação das lâminas com impressões de tecido nervoso em acetona a -20 oC por 30 minutos, pré-adsorção do conjugado com suspensões de NMB e IMB por 60 minutos a 37oC e subseqüente incubação dessas misturas sobre as impressões por 2 horas a 37oC. Estas alterações permitiram a obtenção de uma fluorescência de intensidade sensivelmente maior que a obtida com a metodologia padrão recomendada, aliada a uma completa inibição da fluorescência sobre os controles

Real-time genomic surveillance during the 2021 re-emergence of the yellow fever virus in Rio Grande do Sul state, Brazil

The 2021 re-emergence of yellow fever in non-human primates in the state of Rio Grande do Sul (RS), southernmost Brazil, resulted in the death of many howler monkeys (genus Alouatta) and led the state to declare a Public Health Emergency of State Importance, despite no human cases reported. In this study, near-complete genomes of yellow fever virus (YFV) recovered from the outbreak were sequenced and examined aiming at a better understanding of the phylogenetic relationships and the spatio-temporal dynamics of the virus distribution. Our results suggest that the most likely sequence of events involved the reintroduction of YFV from the state of São Paulo to RS through the states of Paraná and Santa Catarina, by the end of 2020. These findings reinforce the role of genomic surveillance in determining the pathways of distribution of the virus and in providing references for the implementation of preventive measures for populations in high risk areas

Field evaluation of commercial vaccines against Infectious Bovine Rhinotracheitis (Ibr) Virus using different immunization protocols

Bovine alphaherpesvirus 1 is ubiquitous in cattle populations and is associated with several clinical syndromes, including respiratory disease, genital disease, infertility and abortions. Control of the virus in many parts of the world is achieved primarily through vaccination with either inactivated or live modified viral vaccines. The objective of this study was to evaluate the performance of four commercially available BoHV-1 vaccines commonly used in Central and South America. Animals were divided into eight groups and vaccinated on days 0 and 30. Groups 1 to 4 received two doses of four different BoHV-1 commercial vaccines (named A to D). Groups 5 and 6 received vaccine D plus a vaccine for either Clostridial or Food-and-Mouth-Disease (FMD), respectively. Group 7 received one dose of two different brands of reproductive vaccines. Serum samples were collected from all animals on days 0, 30 and 60 to evaluate neutralizing and isotype-specific (IgG1 and IgG2) antibodies. Of the four commercial vaccines evaluated, only vaccine A induced neutralizing antibodies to titers ≥ 1:8 in 13/15 (86%) of the animals 60 days post-vaccination. Levels of IgG2 antibody increased in all groups, except for group 2 after the first dose of vaccine B. These results show that only vaccine A induced significant and detectable levels of BoHV-1-neutralizing antibodies. The combination of vaccine D with Clostridial or FMD vaccines did not affect neutralizing antibody responses to BoHV-1. The antibody responses of three of the four commercial vaccines analyzed here were lower than admissible by vaccine A. These results may be from vaccination failure, but means to identify the immune signatures predictive of clinical protection against BoHV-1 in cattle should also be considered

Um teste simples para o diagnóstico sorológico de infecções pelo herpesvirus bovino tipo 1 (BHV-1)

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Estudo da atividade antiherpética de extratos vegetais

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