Rift Valley fever virus vaccine strategies

Rift Valley fever virus circulates throughout Africa and the Arabian Peninsula and is of great concern for animal and public health. Infections in humans are often manifested as mild self‐limiting illness, although in some cases there are more severe symptoms such as neurological complications and hemorrhagic fever. Spontaneous abortions among livestock are a hallmark for Rift Valley fever virus outbreaks and disease in small ruminants often has a deadly outcome. At present, there is no vaccine available for use in humans and the ones used in livestock are either poorly immunogenic or cause severe adverse effects. The economic impact of this pathogen in the form of livestock losses and restrictions on the trade of animals and animal products as well as its significance in relation to public health underscores the importance of developing safe and effective vaccines. The main focus of this thesis was to evaluate existing vaccines and novel vaccine candidates, with special emphasis on vaccine platforms practical in resource‐poor areas. It is difficult to maintain a cold‐chain during transit in Mozambique and the inactivated Rift Valley fever virus vaccine is transported more than 2000 km within the country before it is administered to livestock in Zambezia Province. For that reason, the vaccine was evaluated for its ability to induce antibodies in cattle after storage at ambient temperatures. Importantly, the storage and transport conditions used in Mozambique did not have an adverse effect on the antibody responses induced by the vaccine. When performing the aforementioned study, we found evidence of previous Rift Valley fever virus infections in livestock in Maputo Province, a region where there had been no recorded evidence of the virus since 1969. A cross‐sectional seroprevalence study was undertaken to examine the need to implement a vaccination program in this particular province. Unexpectedly, seroconversion was observed in 37% of the investigated cattle, suggesting that this pathogen is widely distributed throughout Maputo Province. Rift Valley fever virus is highly pathogenic and to circumvent the handling of replicating virus during the vaccine manufacturing process would be advantageous. Other highly desirable vaccine‐characteristics are low production costs, high immunogenicity to reduce the number of doses, and a non‐invasive delivery route to avoid the challenge of maintaining sterility of hypodermic equipment. To fulfill some of those requirements we developed and evaluated three different vaccine strategies i) DNA vaccines, ii) vaccine based on virus‐like particles, and iii) plant‐derived protein subunit vaccines. All candidates induced vaccine‐specific antibody responses in mice and the DNA‐ and virus‐like particle‐based vaccines conferred protection against Rift Valley fever disease. Here, we raise the question of extending the vaccination program in Mozambique to include Maputo Province. We show that the inactivated virus vaccine is well‐suited for that purpose until more effective alternatives are available. In the search for such an alternative, we evaluated three vaccine candidates. One of those candidates, vaccine based on virus‐like particles, was found to have good prospects as a future Rift Valley fever virus vaccine

Characterisation of immune responses and protective efficacy in mice after immunisation with Rift Valley Fever virus cDNA constructs

<p>Abstract</p> <p>Background</p> <p>Affecting both livestock and humans, Rift Valley Fever is considered as one of the most important viral zoonoses in Africa. However, no licensed vaccines or effective treatments are yet available for human use. Naked DNA vaccines are an interesting approach since the virus is highly infectious and existing attenuated Rift Valley Fever virus vaccine strains display adverse effects in animal trials. In this study, gene-gun immunisations with cDNA encoding structural proteins of the Rift Valley Fever virus were evaluated in mice. The induced immune responses were analysed for the ability to protect mice against virus challenge.</p> <p>Results</p> <p>Immunisation with cDNA encoding the nucleocapsid protein induced strong humoral and lymphocyte proliferative immune responses, and virus neutralising antibodies were acquired after vaccination with cDNA encoding the glycoproteins. Even though complete protection was not achieved by genetic immunisation, four out of eight, and five out of eight mice vaccinated with cDNA encoding the nucleocapsid protein or the glycoproteins, respectively, displayed no clinical signs of infection after challenge. In contrast, all fourteen control animals displayed clinical manifestations of Rift Valley Fever after challenge.</p> <p>Conclusion</p> <p>The appearance of Rift Valley Fever associated clinical signs were significantly decreased among the DNA vaccinated mice and further adjustment of this strategy may result in full protection against Rift Valley Fever.</p

Worsening epidemiological situation of carbapenemase-producing Enterobacteriaceae in Europe, assessment by national experts from 37 countries, July 2018

European Antimicrobial Resistance Genes Surveillance Network (EURGen-Net) capacity survey group (Portugal): Manuela Caniça, Vera Manageiro,A survey on the epidemiological situation, surveillance and containment activities for carbapenemase-producing Enterobacteriaceae (CPE) was conducted in European countries in 2018. All 37 participating countries reported CPE cases. Since 2015, the epidemiological stage of CPE expansion has increased in 11 countries. Reference laboratory capability, dedicated surveillance and a specific national containment plan are in existence in 33, 27 and 14 countries, respectively. Enhanced control efforts are needed for CPE containment in Europe.info:eu-repo/semantics/publishedVersio

Detection of Antibodies against H5 and H7 strains in Birds: Evaluation of Influenza Pseudovirus Particle Neutralization Tests

Introduction: Avian influenza viruses circulate in bird populations, and it is important to maintain and uphold our knowledge of the viral strains that are currently of interest in this context. Here, we describe the use of hemagglutinin-pseudotype retroviruses based on highly pathogenic influenza viruses for the screening of avian sera for influenza A antibodies. Our aim was also to determine whether the pseudovirus neutralization tests that we assessed were sensitive and simple to use compared to the traditional methods, including hemagglutination inhibition assays and microneutralization tests. Material and methods: H5 and H7 pseudovirus neutralization tests were evaluated by using serum from infected rabbits. Subsequently, the assays were further investigated using a panel of serum samples from avian species. The panel contained samples that were seropositive for five different hemagglutinin subtypes as well as influenza A seronegative samples. Results and discussion: The results suggest that the pseudovirus neutralization test is an alternative to hemagglutination inhibition assays, as we observed comparable titers to those of both standard microneutralizations assays as well as hemagglutinin inhibition assays. When evaluated by a panel of avian sera, the method also showed its capability to recognize antibodies directed toward low-pathogenic H5 and H7. Hence, we conclude that it is possible to use pseudoviruses based on highly pathogenic avian influenza viruses to screen avian sera for antibodies directed against influenza A subtypes H5 and H7

Additional file 2: of One-step real-time RT-PCR assays for serotyping dengue virus in clinical samples

Overview of the theoretical specificity towards non-targeted serotypes. The sequences of the primers and probe in the (A) DENV1, (B) DENV2, (C) DENV3, and (D) DENV4 RT-PCR plotted against their respective non-targeted serotypes. Numbers above the primers and probe indicate genomic positions. (PDF 87 kb

Universal Single-Probe RT-PCR Assay for Diagnosis of Dengue Virus Infections

Background: Dengue is a mosquito-borne viral disease that has become more prevalent in the last few decades. Most patients are viremic when they present with symptoms, and early diagnosis of dengue is important in preventing severe clinical complications associated with this disease and also represents a key factor in differential diagnosis. Here, we designed and validated a hydrolysis-probe-based one-step real-time RT-PCR assay that targets the genomes of dengue virus serotypes 1-4. Methodology/Principal Findings: The primers and probe used in our RT-PCR assay were designed to target the 39 untranslated region of all complete genome sequences of dengue virus available in GenBank (n=3,305). Performance of the assay was evaluated using in vitro transcribed RNA, laboratory-adapted virus strains, external control panels, and clinical specimens. The linear dynamic range was found to be 10(4)-10(11) GCE/mL, and the detection limit was between 6.0x10(2) and 1.1x10(3) GCE/mL depending on target sequence. The assay did not cross-react with human RNA, nor did it produce false-positive results for other human pathogenic flaviviruses or clinically important etiological agents of febrile illnesses. We used clinical serum samples obtained from returning travelers with dengue-compatible symptomatology (n = 163) to evaluate the diagnostic relevance of our assay, and laboratory diagnosis performed by the RT-PCR assay had 100% positive agreement with diagnosis performed by NS1 antigen detection. In a retrospective evaluation including 60 archived serum samples collected from confirmed dengue cases 1-9 days after disease onset, the RT-PCR assay detected viral RNA up to 9 days after appearance of symptoms. Conclusions/Significance: The validation of the RT-PCR assay presented here indicates that this technique can be a reliable diagnostic tool, and hence we suggest that it be introduced as the method of choice during the first 5 days of dengue symptoms

Arabidopsis thaliana plants expressing Rift Valley fever virus antigens : Mice exhibit systemic immune responses as the result of oraladministration of the transgenic plants

The zoonotic Rift Valley fever virus affects livestock and humans in Africa and on the Arabian Peninsula.The economic impact of this pathogen due to livestock losses, as well as its relevance to public health,underscores the importance of developing effective and easily distributed vaccines. Vaccines that can bedelivered orally are of particular interest. Here, we report the expression in transformed plants (Arabidopsis thaliana) of Rift Valley fever virusantigens. The antigens used in this study were the N protein and a deletion mutant of the Gn glycoprotein.Transformed lines were analysed for specific mRNA and protein content by RT-PCR and Westernblotting, respectively. Furthermore, the plant-expressed antigens were evaluated for their immunogenicityin mice fed the transgenic plants. After oral intake of fresh transgenic plant material, a proportionof the mice elicited specific IgG antibody responses, as compared to the control animals that were fedwild-type plants and of which none sero-converted. Thus, we show that transgenic plants can be readily used to express and produce Rift Valley Fever virusproteins, and that the plants are immunogenic when given orally to mice. These are promising findingsand provide a basis for further studies on edible plant vaccines against the Rift Valley fever virus.Funding Agencies:Swedish International Development Cooperation Agency (SIDA)Örebro University's Faculty for Business, Science and TechnologySparbanksstiftelsen NyaVaccinutveckling och vaccinproduktio