Fabiana Dal Pozzo

Bovine infection with bluetongue virus with special emphasis on European serotype 8

Bluetongue virus (BTV) is an arthropod-borne virus infecting domestic and wild ruminants. Infection in cattle is commonly asymptomatic and characterised by a long viraemia. Associated with the emergence and the recrudescence of BTV serotype 8 (BTV-8) in Northern and Central Europe, remarkable differences have been noticed in the transmission and in the clinical expression of the disease, with cattle showing clinical illness and reproductive disorders such as abortion, stillbirth and fetal abnormalities. Several investigations have already indicated the putative ability of the European BTV-8 strain to cross the bovine placenta and to cause congenital infections. The current epidemiological and pathological findings present an unusual picture of the disease in affected bovines.

Two alternative inocula to reproduce bluetongue virus serotype 8 disease in calves

The aim of this study was to investigate the consequences in calves of two forms of inocula alternative to the use of wild type infectious blood. Two groups of five calves were infected with low cell-passaged virus and infectious blood issued from one animal passage of the same strain. A longitudinal study was implemented and characterised by clinical standardised observations, haematology, BTV RNA detection and viral isolation from blood, detection of serogroup and neutralising antibodies, cytokine expression and post-mortem examination 46 days post-infection (PI). Both tested inocula were able to reproduce clinical expression of the disease, in the bloodstream viral genome was detected until the end of the experiment while virus isolation was possible between days 7 and 31 PI. Humoral immune response developed earlier in calves infected with low cell-passaged virus, while in both groups a massive antibody production was confirmed by the immune balance between IL-4 and IFN-γ expression. Both tested inocula are presented as valid alternative to the use of wild type infectious blood in the study of the pathogenesis of BTV-8 or the efficacy of current and future vaccines.

Experimental Infection of Sheep at 45 and 60 Days of Gestation with Schmallenberg Virus Readily Led to Placental Colonization without Causing Congenital Malformations.

Background Main impact of Schmallenberg virus (SBV) on livestock consists in reproductive disorders, with teratogenic effects, abortions and stillbirths. SBV pathogenesis and viral placental crossing remain currently poorly understood. Therefore, we implemented an experimental infection of ewes, inoculated with SBV at 45 or 60 days of gestation (dg). Methodology “Mourerous” breed ewes were randomly separated in three groups: eight and nine ewes were subcutaneously inoculated with 1 ml of SBV infectious serum at 45 and 60 dg, respectively (G45 and G60). Six other ewes were inoculated subcutaneously with sterile phosphate buffer saline as control group. All SBV inoculated ewes showed RNAemia consistent with previously published studies, they seroconverted and no clinical sign was reported. Lambs were born at term via caesarian-section, and right after birth they were blood sampled and clinically examined. Then both lambs and ewes were euthanatized and necropsied. Principal Findings/Significance No lambs showed any malformation suggestive of SBV infection and none of them had RNAemia or anti-SBV antibodies prior to colostrum uptake. Positive SBV RNA detection in organs was rare in both G45 and G60 lambs (2/11 and 1/10, respectively). Nevertheless most of the lambs in G45 (9/11) and G60 (9/10) had at least one extraembryonic structure SBV positive by RTqPCR. The number of positive extraembryonic structures was significantly higher in G60 lambs. Time of inoculation (45 or 60 dg) had no impact on the placental colonization success rate but affected the frequency of detecting the virus in the offspring extraembryonic structures by the time of lambing. SBV readily colonized the placenta when ewes were infected at 45 or 60 dg but infection of the fetuses was limited and did not lead to congenital malformations.

Reducing hazards for humans from animals: emerging and re-emerging zoonoses

Pathogens that are capable of infecting more than one host, more than one taxonomic order and wild hosts, all present a higher relative risk of (re-)emergence. A long environmental persistence gives pathogens a more selective advantage. In case of an emerging or re-emerging zoonosis, the prevalence of infection in animals and the exposure determine the incidence in humans. Human exposure to zoonotic agents depends on lifestyle and occupation (e.g., veterinarians and farmers are more at risk for zoonoses related to livestock). Efforts to increase awareness, provide information on prevention, and apply biosecurity are essential. Moreover, a substantial decline in the incidence of human disease implies the prevention, the control or the elimination of zoonoses in the animal compartments. The only way to prevent health hazards is to adapt the existing systems of health governance at global, regional, national and local levels in a harmonised and coordinated manner. To achieve such a goal, the One Health strategy was recently developed to expand interdisciplinary collaborations and communications on all aspects of health care for humans and animals, veterinary, human medical, public health professionals and stakeholders....

Bovine noroviruses: A missing component of calf diarrhoea diagnosis.

Abstract Noroviruses are RNA viruses that belong to the Genus Norovirus, Family Caliciviridae, and infect human beings and several animal species, including cattle. Bovine norovirus infections have been detected in cattle of a range of different ages throughout the world. Currently there is no suitable cell culture system for these viruses and information on their pathogenesis is limited. Molecular and serological tests have been developed, but are complicated by the high genetic and antigenic diversity of bovine noroviruses. Bovine noroviruses can be detected frequently in faecal samples of diarrhoeic calves, either alone or in association with other common enteric pathogens, suggesting a role for these viruses in the aetiology of calf enteritis.

Experimental co-infections of calves with Bluetongue virus serotypes 1 and 8

The contemporary circulation of multiple bluetongue virus (BTV) serotypes or strains within the same territory can imply the co-infection of the ruminant and/or the vector populations. As a consequence, the clinical and pathological outcomes of co-infections as well as the biological properties of the viral progeny could be influenced and exhibit relevant variation. In this study, two independent co-infection experiments were carried out in calves using European strains of BTV serotypes 1 and 8 (BTV-1 and BTV-8, respectively), with the objective of studying the clinical and virological outcomes in comparison with BTV-1 and BTV-8 single infections. Synchronous co-infections using the same titre for the two viral strains were performed and the clinical signs were quantified using a standardized clinical form. Serotype-specific real-time RT-PCRs and viral isolation were used to monitor the course of viraemia. Neutralizing antibody titres were measured during the experiments, and necropsy with viral detection in the affected organs was performed. In the co-infected calves, a high BTV-8 viraemia was detected, while BTV-1 viraemia was irregular and sporadic. During BTV-1 single infection the development of viraemia and high titres of anti-BTV-1 neutralizing antibodies proved that the inoculum was infectious and the detection protocols were efficient. Several hypotheses could explain the predominant detection of BTV-8 in the co-infected calves, such as the occurrence of a privileged BTV-8 segment 2 reassortment, as recently described during in vitro BTV-1/BTV-8 co-infections; interference between the two viral strains; or a higher BTV-8 tropism for the bovine species.

Pulmonary artery haemorrhage in newborn calves following bluetongue virus serotype 8 experimental infections of pregnant heifers.

The emergence of bluetongue disease (BT) among livestock in Europe in 2006 raised many questions including the occurrence and epidemiological significance of foetal infections in cattle. To clarify these aspects, vaccinated and unvaccinated pregnant heifers were sequentially infected twice in an isolation facility (biosafety level 3) with a northern European outbreak strain of Bluetongue virus serotype 8 (BTV-8). The study was terminated 2 months after calving with necropsy of the dams and their offspring. The cattle were monitored throughout the study by clinical scoring and for the presence of circulating neutralising antibodies, and after calving for the presence of infectious virus and viral RNA in blood and milk. Four calves, one born from a vaccinated dam and three from non-vaccinated ones, that were infected at 120 days of gestation had obvious haemorrhage of the pulmonary artery at necropsy. Although haemorrhage of the pulmonary artery is highly characteristic of BT, viral RNA was not detected in any of these calves. Furthermore, although none of the calves born from heifers infected prior to mid-gestation had teratogenic BTV typical brain lesions, some had lesions at birth suggestive of in utero BTV infection. Despite the lack of viral RNA detection, the presence of haemorrhage of the pulmonary artery deserves to be reported as a new observation in the context of the multiple investigations having as main subject the BTV placental crossing in cattle.

Can horses be clinically screened for West Nile Fever

In Europe, the frequency of West Nile Fever (WNF) outbreaks in horses and/or human beings is on the increase, especially in mid-eastern and southern Europe (Dauphin and others 2004, Rabel and others 2011). However, in several western European countries no activity of the virus has been detected so far, for example, in The Netherlands (Rockx and others 2006), Belgium and the UK (Morgan 2006)). However, considering the presence of migratory birds and suitable vectors in those countries, and the reports of changing epidemiology of the virus (Petersen and Marfin 2005, Blitvich 2008), the West Nile virus (WNV) is a genuine threat. Horses are considered good sentinels for WNV infection surveillance (Petersen and Marfin 2005) by the use of syndromic surveillance followed by laboratory confirmation. Syndromic surveillance aims at early identification of disease clusters before laboratory confirmation, thereby reducing morbidity and mortality (Leblond and others 2007). Clinical signs of WNF in horses are, however, difficult to distinguish from those of other neurological diseases (Leblond and others 2007, Porter and others 2011). The aim of this study was to identify clinical variables that could be indicators for WNF in horses, which will be attempted …

Infectivity of a recombinant murine norovirus (RecMNV) in Balb/cByJ mice

The infectivity of a recombinant murine norovirus (RecMNV) strain, previously isolated following in vitro coinfections, was evaluated in vivo in comparison with its parental strains (MNV-1-CW1 and WU20) in Balb/cByJ mice via measurement of weight loss and estimation of viral loads in faeces, tissues and organs 48 and 72h post-infection. The presence of infectious virus in all analysed tissues and organs suggests that, similarly to its parental viruses, RecMNV can disseminate beyond organs associated with the digestive tract. Our results also suggest that recombination occurring in vitro between two homologous murine norovirus strains can give rise to a chimeric strain which, despite slight differences, shows similar biological properties to its parental strains. This study provides the first report on in vivo replication of a recombinant norovirus strain isolated following in vitro coinfection. These results have great significance for norovirus genetic evolution and future vaccine development.

Antiviral agents against equid alphaherpesviruses: Current status and perspectives

Equid herpesvirus infections cause respiratory, neurological and reproductive syndromes. Despite preventive and control measures and the availability of vaccines and immunostimulants, herpesvirus infections still constitute a major threat to equine health and for the equine industry worldwide. Antiviral drugs, particularly nucleoside analogues and foscarnet, are successfully used for the treatment of human alphaherpesvirus infections. In equine medicine, the use of antiviral medications in alphaherpesvirus infections would decrease the excretion of virus and diminish the risk of contagion and the convalescent time in affected horses, and would also improve the clinical outcome of equine herpesvirus myeloencephalopathy. The combined use of antiviral compounds, along with vaccines, immune modulators, and effective preventive and control measures, might be beneficial in diminishing the negative impact of alphaherpesvirus infections in horses. The purpose of this review is to analyse the available information regarding the use of antiviral agents against alphaherpesviruses, with particular emphasis on equine alphaherpesvirus infections.