In vitro replication of bovine herpesvirus types 1 and 5

Bovine alphaherpesvirus type 5 replicates more efficiently than bovine alphaherpesvirus type 1 in undifferentiated human neural cells

Bovine herpesvirus (BoHV) types 1 and 5 are two closely related alpha-herpesviruses of cattle with neuroinvasive potential. BoHV-5 causes non-suppurative meningoencephalitis in calve whereas encephalitis caused by BoHV-1 has been occasionally reported. As an initial step to understand the biology of both BoHV types in neural cells, undifferentiated SH-SY5Y human neuroblastoma cells were infected with BoHV-1 strains Cooper and Los Angeles (LA), BoHV-5 strain 97/613 and A663, a BoHV-5/BoHV-1 natural recombinant. Cytopathic effect (CPE) in these cells was evident earlier for BoHV-5 strain 97/613 and CPE progression was slower for BoHV-1, particularly for Cooper strain. Virus antigen was detected as early as 8 h post-infection (hpi) for all strains, with the exception of BoHV-1 Cooper for which antigen expression was detectable by 24 hpi. All strains released detectable infectious virus in the extracellular medium by 8 hpi, confirming that undifferentiated SH-SY5Y cells are fully permissive to BoHV infection. Significantly different extracellular virus titers among the different strains were detected by 24 hpi, with BoHV-5 97/613 reaching the maximal virus production. The lowest extracellular titer was recorded for BoHV-1 Cooper at all the evaluated time-points. BoHV-1 Cooper, BoHV-1 LA and BoHV-5 97/613 had a steady increase in intracellular virus production. The evaluation of lysis plaques formation revealed that BoHV-5 A663 produced the largest plaques followed by BoHV-5 97/613. Both BoHV-1 strains produced smaller plaques when compared with BoHV-5. Despite a slower replicative cycle, strain A663 is more efficient in cell to cell dissemination. Thus, it is evident that BoHV-5 strains have growth advantages in undifferentiated neural cells compared with BoHV-1. This in vitro model might be useful to analyze the neuropathogenic potential of bovine alphaherpesviruses.

Evaluation of the anti-apoptotic activity of bovine alphaherpesvirus type 5 US3 protein kinase in insect cells using a recombinant baculovirus

Bovine alphaherpesvirus type 5 (BoHV-5) is one of the main agents responsible for meningoencephalitis in cattle in Brazil, causing significant economic losses. It is known that other viruses of the Herpesviridae family such as Bovine alphaherpesvirus type 1, Swine alphaherpesvirus type 1, and the Human alphaherpesvirus types 1 and 2 encode genes homologous to BoHV-5, with recognized action in the control of apoptosis. The objective of this work was to express the BoHV-5 US3 gene in a baculovirus-based expression system for the production of the serine/threonine kinase protein and to evaluate its activity in the control of apoptosis in vitro. A recombinant baculovirus derived from the Autographa californica multiple nucleopolyhedrovirus (AcMNPV) containing the US3 gene and a deletion in the baculovirus anti-apoptotic p35 gene was constructed using the Bac-to-Bac™ system. This recombinant baculovirus was used to evaluate the anti-apoptotic activity of the recombinant US3 protein in insect cells comparing with two other AcMNPV recombinants, one containing a functional copy of the AcMNPV anti-apoptotic p35 gene and an AcMNPV p35 knockout virus with the anti-apoptotic iap-3 gene from Anticarsia gemmatalis multiple nucleopolyhedrovirus (AgMNPV). We found that the caspase level was higher in insect cells infected with the US3-contanining recombinant virus than in cells infected with the AcMNPV recombinants containing the p35 and iap-3 genes. These results indicate that the BoHV-5 US3 protein kinase gene is not able to block apoptosis in insect cells induced by the infection of a p35 knockout AcMNPV.

Comparative analysis of replicative properties of phylogenetically divergent, Argentinean BoHV-4 strains in cell lines from different origins

Bovine gammaherpesvirus 4 (BoHV4) is a member of the family Herpesviridae. In Argentina, BoHV4 was isolated and characterized in 2007 from samples of aborted cows. Argentinean isolates are highly divergent and are classified as: Genotype 1(Movar-like), Genotype 2 (DN599-like) and Genotype 3 (a novel group). The aim of this study was to comparatively evaluate the biological characteristics of six Argentinean BoHV4 field isolates in cell lines from different origins. All strains induced productive infection in the cell lines used, with different degrees of permissiveness. A direct relationship among the times of appearance of cytopathic effect, the growth kinetics, the size of the lysis plaques and the virulent-like behaviour in vitro could not be established. However, although slight, there are differences in the biological behaviour of the BoHV4 fields isolates analyzed. This variability is independent of their genetic classification but would be conditioned by the nature of the infected cells.

Enfermedad neurológica bovina con diagnóstico no conclusivo en la región norte de Colombia. Análisis histológico e inmunohistoquímico

<p>La enfermedad neurológica bovina genera altas pérdidas económicas en las ganaderías y algunos de sus agentes etiológicos son zoonóticos, hechos que hacen prioritario su estudio. El objetivo del trabajo fue identificar antígenos del virus de la rabia y del herpes virus bovino-5 (BoHV-5) en muestras de encéfalos de bovinos archivados como casos de enfermedad neurológica con diagnóstico no conclusivo. Se seleccionaron 10 muestras del laboratorio del Instituto Colombiano Agropecuario -ICA- de Montería. Los tejidos fueron analizados mediante histopatología e inmunohistoquímica; para esta última técnica fueron utilizados tres anticuerpos: dos contra antígenos del virus de la rabia a una dilución de 1:200 y uno contra BoHV-5 a una dilución de 1:100. Histológicamente en nueve casos se observaron lesiones que variaron de tipo y severidad; la identificación de antígenos del virus de la rabia se demostró en 20% (2/10) de los casos y en ningún caso se demostró la presencia BoHV-5. Se discute sobre los resultados histopatológicos e inmunohistoquímicos y se concluye la importancia de asociar los hallazgos de las dos técnicas para establecer la etiología de la enfermedad neurológica, especialmente en casos con diagnóstico inconcluso.</p>

Susceptibility of neuron-like cells derived from bovine Wharton's jelly to bovine herpesvirus type 5 infections

Background

Bovine herpesvirus type 5 (BoHV-5), frequently lethal in cattle, is associated with significant agricultural economic losses due to neurological disease. Cattle and rabbits are frequently used as models to study the biology and pathogenesis of BoHV-5 infection. In particular, neural invasion and proliferation are two of the factors important in BoHV-5 infection. The present study investigated the potential of bovine Wharton’s jelly mesenchymal stromal cells (bWJ-MSCs) to differentiate into a neuronal phenotype and support robust BoHV-5 replication.

Results

Upon inducing differentiation within a defined neuronal specific medium, most bWJ-MSCs acquired the distinctive neuronal morphological features and stained positively for the neuronal/glial markers MAP2 (neuronal microtubule associated protein 2), N200 (neurofilament 200), NT3 (neutrophin 3), tau and GFAP (glial fibrillary acidic protein). Expression of nestin, N200, β-tubulin III (TuJI) and GFAP was further demonstrated by reverse transcriptase polymerase chain reaction (RT-PCR). Following BoHV-5 inoculation, there were low rates of cell detachment, good cell viability at 96 h post-infection (p.i.), and small vesicles developed along neuronal branches. Levels of BoHV-5 antigens and DNA were associated with the peak in viral titres at 72 h p.i. BoHV-5 glycoprotein C mRNA expression was significantly correlated with production of progeny virus at 72 h p.i. (p < 0.05).

Conclusion

The results demonstrated the ability of bWJ-MSCs to differentiate into a neuronal phenotype in vitro and support productive BoHV-5 replication. These findings constitute a remarkable contribution to the in vitro study of neurotropic viruses. This work may pave the way for bWJ-MSCs to be used as an alternative to animal models in the study of BoHV-5 biology.