Peripherally Applied Synthetic Tetrapeptides HAEE and RADD Slow Down the Development of Cerebral ß-Amyloidosis in AßPP/PS1 Transgenic Mice.

Two tetrapeptides, HAEE and RADD, which are ionic-complementary to the primary zinc recognition site of amyloid-ß (Aß), have been reported to inhibit zinc-induced dimerization of the Aß metal-binding domain and slow Aß aggregation in vitro. In the present study, we investigate the impact of HAEE and RADD on the development of cerebral ß-amyloidosis in a mouse model of Alzheimer's disease. We have found chronic intravenous administration of each peptide results in significant decrease of amyloid plaque burden in the treated mice.

Faustovirus-Like Asfarvirus in Hematophagous Biting Midges and Their Vertebrate Hosts.

Faustovirus, a new Asfarviridae-related giant virus, was recently isolated in Vermamoeba vermiformis, a protist found in sewage water in various geographical locations and occasionally reported in human eye infection cases. As part of a global metagenomic analysis of viral communities existing in biting midges, we report here for the first time the identification and isolation of a Faustovirus-like virus in hematophagous arthropods and its detection in their animal hosts. The DNA virome analysis of three pools of Culicoides sp., engorged female Culicoides imicola and non-engorged male/female C. imicola biting midges collected in Senegal, revealed the presence of amoeba-infecting giant viruses and, among them, a majority of sequences related to Faustovirus. Phylogenetic analyses conducted on several structural genes of Faustovirus confirmed the clustering of the arthropod-borne Faustovirus with sewage-borne Faustoviruses, with a distinct geographical clustering of Senegalese Faustovirus strains. Transmission electron microscopy identified viral particles with morphologies and diameters which were compatible with Faustovirus. The presence of infectious arthropod-borne Faustovirus was finally confirmed by successful isolation on V. vermiformis amoeba. Global proteomic analysis of biting midges identified that arthropods' blood meal originating from cattle, rodents and humans. Further screening of cattle sera and rodent tissue resulted in prevalence of Faustovirus being estimated at 38% in rodents and 14% in cattle, suggesting a possible origin of Faustovirus presence in arthropods via the ingestion of contaminated blood meal. Viral loads were the highest in rodents' urine and kidney samples, suggesting a possible excretion of viral particles into the environment. Faustovirus DNA polymerase-related sequences were also detected in more than 9 and 11% of febrile patients and healthy Senegalese human sera, respectively. Our study thus, highlights the need to investigate the role of arthropods, wildlife, and domestic animals in the lifecycle of amoeba-infecting giant viruses and, in particular, the environmental cycle of Faustovirus.

Rickettsial diseases in Russia.

Currently, several rickettsioses are officially being reported in the Russian Federation. These are epidemic typhus and Brill-Zinsser disease, both caused by Rickettsia prowazekii which has a historic prevalence in Russia. Nowadays only single sporadic cases of R. prowazekii infection are reported. The last significant outbreak occurred in 1997 in a mental nursing home, where 29 cases were identified. Registered morbidity of typhus in Russia varies from 0 to 0.01 per thousand for the last decade. Siberian tick typhus, caused by R. sibirica, is registered on a large territory from Pacific coasts to Western Siberia, and its incidence continuously increases, varying between 2.5 and 4.0 thousand officially registered cases per year. Astrakhan spotted fever, caused by R. conorii subsp. caspia has been recognized since 1983. Recently, Far Eastern tick-borne rickettsiosis, caused by R. heilongjiangensis, has been described. Several other pathogenic spotted fever group rickettsiae have been detected and isolated from ticks in Russia; however, they have not yet been linked with clinical cases in these regions.

Diversity of Borrelia burgdorferi sensu lato in Russian Far East.

Thirty strains of Borrelia burgdorferi sensu lato have been isolated from Ixodes persulcatus ticks and from skin lesions of Lyme disease patients in the Russian Far East from 1997 to 2003. We amplified full-length outer surface protein A (ospA) gene of all strains. BLAST search and following phylogenetic analysis showed that strains form four well-defined groups. Four strains belong to Borrelia afzelii species. Other strains distributed into tree major groups, identified as Borrelia garinii. Indeed, based on the ospA gene comparison, phylogenetic relationship of these groups among each other does not differ from relationship among other previously defined groups inside B. burgdorferi sensu lato genogroup, such as B. afzelii or Borrelia bissettii. Further investigations of genetic and serologic properties of the strains belonging to those groups are required in order to clarify their taxonomic status.

Acute tick-borne rickettsiosis caused by Rickettsia heilongjiangensis in Russian Far East.

An acute tick-borne rickettsiosis caused by Rickettsia heilongjiangensis was diagnosed in 13 patients from the Russian Far East in 2002. We amplified and sequenced four portions of three rickettsial genes from the patients' skin biopsy results and blood samples and showed that the amplified rickettsial genes belong to R. heilongjiangensis, which was recently isolated from Dermacentor sylvarum ticks in nearby regions of China. This rickettsia, belonging to subgroup of R. japonica, was previously suggested to be pathogenic for humans on the basis of serologic findings. We tested serum samples with different rickettsial antigens from 11 patients and confirmed increasing titers of immunoglobulin (Ig) G and IgM to spotted fever group rickettsiae, including R. heilongjiangensis. Clinical and epidemiologic data on these patients show that this disease is similar to other tick-borne rickettsioses.