Rabbit haemorrhagic disease virus 2 (RHDV2) outbreak in Azores: Disclosure of common genetic markers and phylogenetic segregation within the European strains

Rabbit haemorrhagic disease virus 2 (RHDV2) is widespread in several countries of Western Europe, but it has not been introduced to other continents. However, between late 2014 and early 2015, the presence of RHDV2 was confirmed outside of the European continent, in the Azores, initially in the islands of Graciosa, Flores, S. Jorge and Terceira. In this study we report the subsequent detection of RHDV2 in wild rabbits from the islands of Faial, St. Maria and S. Miguel, and display the necropsy and microscopic examination data obtained, which showed lesions similar to those induced by classical strains of RHDV, with severe affection of lungs and liver. We also disclose the result of a genetic investigation carried out with RHDV2 positive samples from wild rabbits found dead in the seven islands. Partial vp60 sequences were amplified from 27 tissue samples. Nucleotide analysis showed that the Azorean strains are closely related to each other, sharing a high genetic identity (>99.15%). None of the obtained sequences were identical to any RHDV2 sequence publically known, hampering a clue for the source of the outbreaks. However, Bayesian and maximum likelihood phylogenetic analyses disclosed that Azorean strains are more closely related to a few strains from Southern Portugal than with any others presently known. In the analysed region comprising the terminal 942 nucleotides of the vp60 gene, four new single nucleotide polymorphisms (SNP) were identified. Based on the present data, these four SNPs, which are unique in the strains from Azores, may constitute putative molecular geographic markers for Azorean RHDV2 strains, if they persist in the future. One of these variations is a non-synonymous substitution that involves the replacement of one amino acid in a hypervariable region of the capsid protein.

[Devic disease: a case report]

OBJECTIVE: To report a case of Devic disease, emphasizing its diagnosis, in addition to reviewing the medical literature. DESCRIPTION: Male, six-year-old patient suddenly developed weakness in lower limbs, with resolution during hospital stay. However, as the weakness disappeared, loss of vision occurred. The symptoms were reverted after the use of prednisone. COMMENTS: The diagnostic and therapeutic approach was similar to that used in other cases reported by different reference centers. In other words, clinical diagnosis and prednisone therapy were used, with the complete improvement of symptoms. However, there is still some controversy surrounding its etiology and relationship with other demyelinating diseases, such as multiple sclerosis.

In vivo and in vitro effect of imipramine and fluoxetine on Na+,K+-ATPase activity in synaptic plasma membranes from the cerebral cortex of rats

The effects of in vivo chronic treatment and in vitro addition of imipramine, a tricyclic antidepressant, or fluoxetine, a selective serotonin reuptake inhibitor, on the cortical membrane-bound Na+,K+-ATPase activity were studied. Adult Wistar rats received daily intraperitoneal injections of 10 mg/kg of imipramine or fluoxetine for 14 days. Twelve hours after the last injection rats were decapitated and synaptic plasma membranes (SPM) from cerebral cortex were prepared to determine Na+,K+-ATPase activity. There was a significant decrease (10%) in enzyme activity after imipramine but fluoxetine treatment caused a significant increase (27%) in Na+,K+-ATPase activity compared to control (P<0.05, ANOVA; N = 7 for each group). When assayed in vitro, the addition of both drugs to SPM of naive rats caused a dose-dependent decrease in enzyme activity, with the maximal inhibition (60-80%) occurring at 0.5 mM. We suggest that a) imipramine might decrease Na+,K+-ATPase activity by altering membrane fluidity, as previously proposed, and b) stimulation of this enzyme might contribute to the therapeutic efficacy of fluoxetine, since brain Na+,K+-ATPase activity is decreased in bipolar patients.

Methylmalonate administration decreases Na+,K+-ATPase activity in cerebral cortex of rats

Buffered methylmalonate (MMA) was injected s.c. into rats twice a day at 8 h intervals from 5 to 25 days of age (chronic treatment), or into 10-day-old rats three times a day at 1 h intervals (acute treatment). Control rats received saline in the same volumes. Na+,K+-ATPase and Mg2+-ATPase activities were determined in the synaptic plasma membranes from cerebral cortex of rats. Na+,K+-ATPase activity was reduced by 30-40% in MMA-treated rats, whereas Mg2+-ATPase activity was not. In contrast, MMA at final concentrations ranging from 0.1 to 2.0 mM had no in vitro effect on these enzyme activities. However, when brain homogenates were incubated with 2 mM MMA before membrane preparation, Na+,K+-ATPase activity was decreased by 44%. Furthermore, this reduction was totally prevented by the simultaneous addition of glutathione and MMA, suggesting that oxidation of thiol groups or other oxidative damage to the enzyme could be responsible for this effect.