26 research outputs found
Development and efficacy testing of inactivated vaccines against Schmallenberg virus infection in cattle and sheep
No full textDevelopment and efficacy testing of inactivated vaccines against Schmallenberg virus infection in cattle and sheep
No full textEvaluating the protective efficacy of a trivalent vaccine containing Akabane virus, Aino virus and Chuzan virus against Schmallenberg virus infection
No full textSchmallenberg virus (SBV), an arthropod borne pathogen, spread rapidly throughout the majority of Europe since 2011. It can cause a febrile disease, milk drop, diarrhea, and fetal malformation in ruminants. SBV, a member of the Simbu serogroup within the genus Orthobunyavirus, is closely related to Akabane virus (AKAV) and Aino virus (AINOV) among others. In the present study, 4 Holstein-Friesian calves were immunized twice four weeks apart with a multivalent, inactivated vaccine against AKAV and AINOV. Another 4 calves were kept as unvaccinated controls. All animals were clinically, serologically and virologically examined before and after challenge infection with SBV. AKAV- and AINOV-specific neutralizing antibodies were detected one week before challenge infection, while SBV-specific antibodies were detectable only thereafter. SBV genome was detected in all vaccinated animals and 3 out of 4 controls in serum samples taken after challenge infection. In conclusion, the investigated vaccine was not able to prevent an SBV-infection. Thus, vaccines for other related Simbu serogroup viruses can not substitute SBV-specific vaccines as an instrument for disease control
Single immunization with an inactivated vaccine protects sheep from Schmallenberg virus infection
No full textInternational audienceAbstractThe arthropod-borne Schmallenberg virus (SBV), family Orthobunyaviridae, emerged in Europe in 2011. SBV is associated with a mild disease in adult ruminants but fetal malformation after an infection during a critical phase of pregnancy. A number of inactivated vaccines have been developed; their efficacy after two injections was demonstrated. To make the vaccination of sheep more efficient and economic the effect of a single immunization with one of these vaccines was investigated in the present study. Five vaccinated sheep and five additional control sheep were inoculated with SBV three weeks after vaccination and the results of a competitive ELISA, a standard microneutralization test and an SBV-specific real-time RT-PCR confirmed vaccine efficacy by demonstrating complete inhibition of viral replication in immunized animals
Detection of canine adenovirus 1 in red foxes (<i>Vulpes vulpes</i>) and raccoons (<i>Procyon lotor</i>) in Germany with a TaqMan real-time PCR assay
No full text We developed a real-time (rt)PCR assay based on TaqMan probe technology for the specific detection of canine adenovirus 1 (CAdV-1). The assay is able to detect three 50% tissue culture infectious dose/mL in CAdV-1–containing cell culture supernatant. Viral genomes were not amplified of canine adenovirus 2 or of several bovine, porcine, and avian adenoviruses. In silico analysis provided no indication of amplification of other heterologous genomes. The sensitivity of the real-time assay exceeded that of a conventional gel-based CAdV-1 PCR by a factor of 100. Following the integration of the novel PCR into the Hessian wildlife-monitoring program, CAdV-1 DNA was detected in none of the tested raccoons ( n = 48) but in 11 of 97 foxes. </jats:p
Inactivated Schmallenberg virus prototype vaccines
No full textSchmallenberg virus (SBV), a novel Orthobunyavirus, is an insect-transmitted pathogen and was first described in Europe in 2011. SBV causes a mild transient disease in adult ruminants, but severe foetal malformation and stillbirth were observed after an infection of naive cows and ewes, which is responsible for considerable economic losses. The virus is now widely distributed in Europe, and no vaccines were available to stop transmission and spread.
In the present study, 16 calves and 25 sheep, the major target species of SBV infection, were vaccinated twice 3 weeks apart with one of 5 newly developed, inactivated vaccine candidates. Six calves and 5 sheep were kept as unvaccinated controls. All animals were clinically, serologically and virologically examined before and after challenge infection.
Immunisation with the inactivated preparations resulted in a neutralising antibody response three weeks after the second vaccination without any side effects. The number of animals that seroconverted in each group and the strength of the antibody response were dependent on the cell line used for virus growth and on the viral titre prior to inactivation. Four vaccine prototypes completely prevented RNAemia after challenge infection, a fifth candidate reduced RNAemia considerably. Although further evaluations e.g. regarding duration of immunity will be necessary, the newly developed vaccines are promising candidates for the prevention of SBV-infection and could be a valuable tool in SBV control strategies
Within-Host Dynamics of Multi-Species Infections:Facilitation, Competition and Virulence
No full textHost individuals are often infected with more than one parasite species (parasites defined broadly, to include viruses and bacteria). Yet, research in infection biology is dominated by studies on single-parasite infections. A focus on single-parasite infections is justified if the interactions among parasites are additive, however increasing evidence points to non-additive interactions being the norm. Here we review this evidence and theoretically explore the implications of non-additive interactions between co-infecting parasites. We use classic Lotka-Volterra two-species competition equations to investigate the within-host dynamical consequences of various mixes of competition and facilitation between a pair of co-infecting species. We then consider the implications of these dynamics for the virulence (damage to host) of co-infections and consequent evolution of parasite strategies of exploitation. We find that whereas one-way facilitation poses some increased virulence risk, reciprocal facilitation presents a qualitatively distinct destabilization of within-host dynamics and the greatest risk of severe disease.</p
Fetal infection with Schmallenberg virus – an experimental pathogenesis study in pregnant cows
No full textSince its first appearance in 2011, Schmallenberg virus (SBV) has been repeatedly detected in aborted ruminant fetuses or severely malformed newborns whose mothers were naturally infected during pregnancy. However, especially the knowledge about dynamics of fetal infection in cattle is still scarce. Therefore, a total of 36 pregnant heifers were experimentally infected during two animal trials with SBV between days 60 and 150 of gestation. The fetuses were collected between 10 and 35 days after infection and virologically and pathologically investigated. Overall, 33 heifers yielded normally developed, macroscopically inconspicuous fetuses, but abundant virus replication was evident at the maternal/fetal interface and viral genome was detectable in at least one organ system of 18 out of 35 fetuses. One heifer was found to be not pregnant at autopsy. One of the animals aborted at day 4 after infection, viral RNA was detectable in the lymphatic tissue of the dam, in the maternal and fetal placenta, and in organs and lymphatic tissue of the fetus. In another fetus, SBV typical malformations like torticollis and arthrogryposis were observed. The corresponding dam was infected at day 90 of pregnancy and viral genome was detectable in the cerebellum of the unborn.
Interestingly, no common patterns of infected fetal organs or maternal/fetal placentas could be identified, and both sites of virus replication and genome loads varied to a high degree in the individual fetuses. It is therefore concluded, that SBV infects in many cases also the bovine fetus of naïve pregnant cattle, however, the experimentally observed low abortion/malformation rate is in concordance to the reported low rates in the field during the first outbreak wave following the introduction of SBV. This observation speaks for a natural resistance of most bovine fetuses even during the vulnerable phase of early pregnancy, which has to be further studied in the future
