Ozone and photodynamic inactivation of norovirus surrogate bacteriophage MS2 in fresh Brazilian berries and surfaces.

This study assessed the efficacy of ozone (bubble diffusion in water; 6.25 ppm) and photodynamic inactivation (PDT) using curcumin (75 µM) as photosensitizer (LED emission 430-470 nm; 33.6 mW/cm2 irradiance; 16.1, 20.2, and 24.2 J/cm2 light dose) against the Norovirus surrogate bacteriophage MS2 in Brazilian berries (black mulberry and pitanga) and surfaces (glass and stainless steel). Contaminated berries and surfaces were immersed in ozonized water or exposed to PDT-curcumin for different time intervals. Transmission electron microscopy was used to assess the effects of the treatments on MS2 viral particles. The MS2 inactivation by ozone and PDT-curcumin varied with the fruit and the surface tested. Ozone reduced the MS2 titer up to 3.6 log PFU/g in black mulberry and 4.1 log PFU/g in pitanga. On surfaces, the MS2 reduction by ozone reached 3.6 and 4.8 log PFU/cm2 on glass and stainless steel, respectively. PDT-curcumin reduced the MS2 3.2 and 4.8 log PFU/g in black mulberry and pitanga and 2.7 and 3.3 log PFU/cm2 on glass and stainless steel, respectively. MS2 particles were disintegrated by exposure of MS2 to ozone and PDT-curcumin on pitanga. Results can contribute to establishing effective practices for controlling NoV in fruits and surfaces, estimated based on MS2 bacteriophage behavior.

Chikungunya virus infection induces ultrastructural changes and impaired neuronal differentiation of human neurospheres.

Chikungunya virus (CHIKV) is an arthropod-borne virus recently associated with large outbreaks in many parts of the world. Infection is typically manifested as a febrile and self-limited illness, characterized by joint pain and myalgia, albeit severe neurological manifestations are also reported. Although CHIKV is not recognized as a truly neurotropic virus, neurons, astrocytes, and oligodendrocytes are susceptible to infection in vitro. Here we employed a model of 3D cell culture to obtain neurospheres from ATRA/BNDF differentiated human neuroblastoma cells. We demonstrate that CHIKV is able to establish a productive infection, resulting in ultrastructural changes in cell morphology and impaired neuronal differentiation. Ultrastructural analysis of neurospheres infected with CHIKV during neuronal differentiation revealed diminished neuron dendrite formation, accumulation of viral particles associated with the plasma membrane, numerous cell vacuoles, and swollen mitochondria. Apoptotic cells were significantly increased at 72 h post-infection. Compared to Zika virus, a well-characterized neurotropic arbovirus, CHIKV infection resulted in a more discrete, albeit detectable upregulation of IL-6 levels. Finally, we found that CHIKV infection resulted in an altered profile expression, mainly downregulation, of a group of transcription factors named Hox genes. Altogether our findings highlight important features of CHIKV in the CNS, as well as the feasibility of neurospheres as robust experimental models that can support further studies for novel pharmacological interventions.