Isolation of a bovine adenovirus serotype 10 from a calf in the United States

Recombinant hexon protein as a new bovine adenovirus type 3 subunit vaccine candidate

Introduction

Bovine adenovirus (BAdV) type 3 causes respiratory and gastroenteric diseases of varying severity in cattle, particularly newborn calves. Trials have been conducted of a vaccination against the diseases caused by BAdV using both modified live-virus and inactivated-virus preparations in cattle, but no commercial BAdV-3 vaccine has yet reached the market. Therefore, there is an urgent need to develop new, safe, and effective vaccines against BAdV-3.

Material and Methods

Recombinant hexon protein (rhexon) of BAdV-3 was expressed in the E. coli system to evaluate immune response in mice and goats. Antibody responses and cytokine levels were analysed and the effects of administrations of different amounts of recombinant protein compared. Long-term antibody production was evaluated by indirect ELISA, and the total immunoglobulin G secreted by goats and mice immunised with the purified rhexon protein was determined.

Results

The immunised mice had a stronger antibody response than the control group at eight weeks post vaccination. The immunised groups also showed significantly higher (P ˂ 0.05) expression of interferon-γ, interleukin 2 (in mice), and interleukin 21 (in goats) at four weeks. Furthermore, vaccination with rhexon was able to induce long-term antibody production for at least 16 weeks in mice and goats.

Conclusion

The rhexon protein induced immune responses, especially long-term antibody production and T helper 1 cell cytokine production in mice and goats. The immunogenic properties of this protein make it a promising subunit vaccine antigen.

First DNA sequence proof for the occurrence of bovine adenovirus types 10 and 11 in continental Europe

Bovine adenoviruses (BAdV) are known to cause respiratory and/or intestinal disease in calves. Infection can manifest as acute outbreaks, but more often only sporadic cases occur. Here we describe the PCR detection and partial sequence characterization of several BAdVs found in sick or dead calves on different farms in Western Hungary. Intermittent diarrhoeal illnesses occurred after weaning among calves on several farms located up to 40 km apart. A high-sensitivity, broad-spectrum nested PCR, developed for the general detection of adenoviruses, gave positive results in four independent cases. Direct sequencing of PCR products showed clear results from only two samples, whereas sequences from the other two amplicons were mixed. Molecular cloning of these heterogeneous PCR products was performed to separate each DNA fragment therein. By sequencing several plasmid clones from both mixed samples, we were able to detect the simultaneous presence of two different BAdV types, namely types 6 and 10 classified into two separate (Atadenovirus and Mastadenovirus) genera. The sequence of one homogenous sample was identified as being derived also from BAdV-10, whereas the other sample contained a novel type, proposed to be BAdV-11. We demonstrated, for the very first time, the occurrence of the two latter virus types in continental Europe. Their appearance in Hungary marks a significant shift in the types of BAdVs actually circulating in the country. Considering the similarity of the pathological findings to those, attributed to BAdV-10 infections reported to date, the causative role of the viruses in these cases seems to be plausible. Phylogeny reconstruction further confirmed that BAdVs represent multiple genetic lineages.

Novel adenoviruses detected in British mustelids, including a unique Aviadenovirus in the tissues of pine martens (Martes martes)

Several adenoviruses are known to cause severe disease in veterinary species. Recent evidence suggests that canine adenovirus type 1 (CAV-1) persists in the tissues of healthy red foxes (Vulpes vulpes), which may be a source of infection for susceptible species. It was hypothesized that mustelids native to the UK, including pine martens (Martes martes) and Eurasian otters (Lutra lutra), may also be persistently infected with adenoviruses. Based on high-throughput sequencing and additional Sanger sequencing, a novel Aviadenovirus, tentatively named marten adenovirus type 1 (MAdV-1), was detected in pine marten tissues. The detection of an Aviadenovirus in mammalian tissue has not been reported previously. Two mastadenoviruses, tentatively designated marten adenovirus type 2 (MAdV-2) and lutrine adenovirus type 1 (LAdV-1), were also detected in tissues of pine martens and Eurasian otters, respectively. Apparently healthy free-ranging animals may be infected with uncharacterized adenoviruses with possible implications for translocation of wildlife.

Clinicopathological features of 11 suspected outbreaks of bovine adenovirus infection and development of a real-time quantitative PCR to detect bovine adenovirus type 10

CASE HISTORY

A retrospective study was conducted to investigate 11 outbreaks of presumptive fatal adenovirus infection diagnosed through two New Zealand diagnostic laboratories during 2014 and 2015. Outbreaks occurred in 6-12-month-old Friesian or Friesian cross cattle during autumn, winter and spring. Individual outbreaks were short in duration, with mortality rates ranging from 3/250 to 20/600 (1.2 to 3.3%).

CLINICAL AND PATHOLOGICAL FINDINGS

Clinical signs included severe diarrhoea, depression, recumbency, and death. Post-mortem examination revealed congestion and oedema of the alimentary tract and fluid to haemorrhagic intestinal contents. Histopathological lesions were characterised by congestion and haemorrhage of the alimentary tract mucosa, oedema of the submucosa, and mild interstitial inflammation in the kidneys. Large basophilic intranuclear inclusion bodies were identified in vascular endothelial cells of the alimentary tract in 11/11 cases and of the kidney in 8/9 cases.

MOLECULAR TESTING

A real-time quantitative PCR (qPCR) assay was designed to detect bovine adenovirus type 10 (BAdV-10) using hexon gene sequences available in GenBank. DNA extracted from a field case and confirmed by sequencing was used as a positive control. The qPCR had a reaction efficiency of 101% (R(2)=0.99) and the limit of detection was <10 DNA copies/reaction. The qPCR detected BAdV-10 in formalin-fixed paraffin-embedded (FFPE) tissue from 10/11 cases. DNA sequencing of PCR products from nine of these cases showed them to be identical to BAdV-10 sequences in GenBank. For the PCR-negative case, the PCR product had a hexon sequence 99% similar to bovine adenovirus Wic isolate Ma20-1, a close relative of BadV-10.

DIAGNOSIS

Bovine adenovirus type 10 was identified in FFPE tissues from cattle with histopathological evidence of adenovirus infection.

CLINICAL RELEVANCE

Bovine adenoviruses, and especially BAdV-10, should be considered in the differential diagnosis for acute enteric disease and death in young cattle. The qPCR detected BAdV-10 from FFPE tissue of cattle with suspected adenoviral infection diagnosed by histopathology. However results should be interpreted in light of clinical and pathological findings due to the possibility of adenovirus shedding by healthy cattle and the presence of pathogenic adenoviruses other than BAdV-10.

Detection of known and novel adenoviruses in cattle wastes via broad-spectrum primers

The critical assessment of bovine adenoviruses (BAdV) as indicators of environmental fecal contamination requires improved knowledge of their prevalence, shedding dynamics, and genetic diversity. We examined DNA extracted from bovine and other animal waste samples collected in Wisconsin for atadenoviruses and mastadenoviruses using novel, broad-spectrum PCR primer sets. BAdV were detected in 13% of cattle fecal samples, 90% of cattle urine samples, and 100% of cattle manure samples; 44 percent of BAdV-positive samples contained both Atadenovirus and Mastadenovirus DNA. Additionally, BAdV were detected in soil, runoff water from a cattle feedlot, and residential well water. Overall, we detected 8 of 11 prototype BAdV, plus bovine, rabbit, and porcine mastadenoviruses that diverged significantly from previously reported genotypes. The prevalence of BAdV shedding by cattle supports targeting AdV broadly as indicators of the presence of fecal contamination in aqueous environments. Conversely, several factors complicate the use of AdV for fecal source attribution. Animal AdV infecting a given livestock host were not monophyletic, recombination among livestock mastadenoviruses was detected, and the genetic diversity of animal AdV is still underreported. These caveats highlight the need for continuing genetic surveillance for animal AdV and for supporting data when BAdV detection is invoked for fecal source attribution in environmental samples. To our knowledge, this is the first study to report natural BAdV excretion in urine, BAdV detection in groundwater, and recombination in AdV of livestock origin.

DNA sequencing and analysis of the right-hand part of the genome of the unique bovine adenovirus type 10

The prototype strain of bovine adenovirus (BAdV) type 10 and four additional isolates that were indistinguishable in serum-neutralization tests have been shown to have remarkable variation in their genome size and restriction maps. In the present study, more than 40 % of the DNA sequence of the BAdV-10 isolate with the longest genome was determined. A biased base composition resulting in low (<41 %) GC content was noticed. Analysis of the genes of the DNA-binding protein, 100K, 33K, pVIII and fibre proteins, as well as early regions E3 and E4, which are encoded by the genome fragment examined, confirmed that BAdV-10 is different from the other known BAdV types regarding its phylogenetic distance and the organization of its exceptionally short E3 region, apparently containing only two genes. A comparative analysis of the E3 and E4 regions of BAdV-10 with various animal adenoviruses revealed interesting features accounting for the very short genome of BAdV-10. In the examined BAdV-10 isolate, duplicated sequences were localized in and around the fibre gene. Since BAdV-10 appears to be pathogenic to cattle and is genetically distant from the other BAdVs, we suggest that BAdV-10 is not a genuine bovine virus, but has recently switched host and is now undergoing an adaptation process in its new host. In accordance with this hypothesis, the remarkable predominance of AT-rich codons along with the variable fibre gene might be signs of adaptation.

Bovine adenovirus serotype 7 infections in postweaning calves

OBJECTIVE

To detect bovine adenovirus serotype 7 (BAV-7) infections in calves by use of viral isolation and serologic testing.

ANIMALS

205 postweaning calves.

PROCEDURE

121 calves were assembled by an order buyer through auction markets in eastern Tennessee and transported to New Mexico where they were commingled with 84 healthy ranch-reared calves. Tests included viral isolation in cell culture from peripheral blood leukocytes (PBL) and detection of serum BAV-7 antibodies by use of microtitration viral neutralization.

RESULTS

BAV-7 was isolated from PBL of 8 calves and seroconversion to BAV-7 was detected for 38 of 199 (19.1%) calves. Concurrent bovine viral diarrhea virus infections were detected in most calves from which BAV-7 was isolated.

CONCLUSIONS AND CLINICAL RELEVANCE

Results of our study indicate that BAV-7 infections can be found in postweaning commingled calves and may develop more commonly in calves with concurrent infections with viruses such as bovine viral diarrhea virus (BVDV).

Endometritis in postparturient cattle associated with bovine herpesvirus-4 infection: 15 cases

Suppurative, ulcerative endometritis associated with bovine herpesvirus-4 (BHV-4) infection was identified in 15 postparturient dairy cows from 5 separate dairies. Characteristic eosinophilic to amphophilic intranuclear viral inclusion bodies were identified within degenerate endometrial lining epithelium and endothelial cells. Bovine herpesvirus-4 was confirmed as the etiology by a combination of fluorescent antibody assays, viral isolation, heminested PCR, ultrastructural examination of the uterus and inoculated tissue culture cells, and negative-stain electron microscopy of tissue culture supernatant. Viral particles measuring 70-95 nm were demonstrated in uterine epithelial and endothelial cells by electron microscopy. Bacteria including Arcanobacterium pyogenes, Escherichia coli, and an alpha-Streptococcus isolate were isolated from all uteri. Bovine herpesvirus-4-associated endometritis has been previously reported in sporadic cases in Europe but has not been previously reported in the United States. Endometritis associated with BHV-4 appears to be an emerging syndrome in Georgia dairy herds.