Mongrelised genetics of H1N1 virus: A bird's eyeview.

H1N1 influenza, also known as "novel H1N1 virus" has led to a "global outcry." This virus is more virulent when compared with other seasonal flu viruses. Virulence may change as the adaptive mutation gene increases within the virus. A study at the US Centre for Disease Control and Prevention published in May 2009 found that children had no preexisting immunity to the new strain as they showed no cross-reactive antibody reaction when compared with adults aged 18-64 years, who showed a cross-reactive antibody reaction of 6-9% and older adults with 33% immunity. This review article depicts H1N1 virus, its virulence with genetic evolution potential and preventive protocol for the dental professionals. This would allow us to comprehend the changes in the disease process and contribute in its prevention as "prevention is better than cure."

In vivo morphological and antigenic characteristics of Photobacterium damselae subsp. piscicida

The present study was conducted to examine the morphology and antigenicity of Photobacterium damselae subsp. piscicida by culturing the bacterium in vivo in the peritoneal cavity of sea bass (Dicentrarchus labrax) within dialysis bags with either a low molecular weight (LMW) cut-off of 25 kDa or a high molecular weight (HMW) cut-off of 300 kDa. Differences were observed in the growth rate between the bacteria cultured in vivo or in vitro. Bacteria cultured in vivo were smaller and produced a capsular layer, which was more prominent in bacteria cultured in the HMW bag. Antigenicity was examined by Western blot analysis using sera from sea bass injected with live Ph. d. subsp. piscicida. The sera recognised bands at 45 and 20 kDa in bacteria cultured in vivo in the LMW bag. Bacteria cultured in vivo in the HMW bag did not express the 45 kDa band when whole cell extracts were examined, although the antigen was present in their extracellular products. In addition, these bacteria had a band at 18 kDa rather than 20 kDa. Differences in glycoprotein were also evident between bacteria cultured in vitro and in vivo. Bacteria cultured in vitro in LMW and HMW bags displayed a single 26 kDa band. Bacteria cultured in the LMW bag in vivo displayed bands at 26 and 27 kDa, while bacteria cultured in vivo in the HMW bag possessed only the 27 kDa band. These bands may represent sialic acid. The significance of the changes observed in the bacterium's structure and antigenicity when cultured in vivo is discussed.

Rapid turnover of Plasmodium falciparum var gene transcripts and genotypes during natural non-symptomatic infections

Os genes var de Plasmodium falciparum codificam as proteínas variantes da superfície do eritrócito infectado (PfEMP1). Neste estudo examinamos a mudança de transcritos destes genes var em duas infecções assintomáticas durante um curto prazo e estimamos simultaneamente o número de genomas circulantes nas mesmas amostras por análise de microssatélites. Nas duas infecções observamos uma rápida mudança de genótipos e transcritos de genes var. A mudança acelerada do repertório de transcritos possivelmente foi causada pela rápida eliminação de parasitas circulantes transcrevendo genes var a partir de genomas iguais ou diferentes, ou pela mudança acelerada da própria transcrição (switching) de genes var.

Molecular epidemiology of human respiratory syncytial virus in Uruguay: 1985-2001 - A review

The variability of the G glycoprotein from human respiratory syncytial viruses (HRSV) (groups A and B) isolated during 17 consecutive epidemics in Montevideo, Uruguay have been analyzed. Several annual epidemics were studied, where strains from groups A and B circulated together throughout the epidemics with predominance of one of them. Usually, group A predominates, but in some epidemics group B is more frequently detected. To analyse the antigenic diversity of the strains, extracts of cells infected with different viruses of group A were tested with a panel of anti-G monoclonal antibodies (MAbs). The genetic variability of both groups was analyzed by sequencing the C-terminal third of the G protein gene. The sequences obtained together with previously published sequences were used to perform phylogenetic analyses. The data from Uruguayan isolates, together with those from the rest of the world provide information regarding worldwide strain circulation. Phylogenetic analyses of HRSV from groups A and B show a model of evolution analogous to the one proposed for influenza B viruses providing information that would be beneficial for future immunization programs and to design safe vaccines.

Control of gene expression and genetic manipulation in the Trypanosomatidae

Mechanisms controlling gene expression in trypanosomatids depend on several layers of regulation, with most regulatory pathways acting at a post-transcriptional level. Consequently, these parasites can follow the rapid changes associated with transitions between the insect vector and the mammalian host, with instant reprogramming of genetic expression. Using primarily Trypanosoma brucei as a model, the basic controlling mechanisms have been elucidated and now researchers are beginning to define the cellular factors involved in the transcription, processing and translation of the mRNAs in these parasites. We describe some of the studies made on a subset of genes that are differentially expressed during the life cycles of T. brucei and T. cruzi. It is becoming evident that the regulatory strategies chosen by different species of trypanosomatids are not the same, and therefore, the lessons learned from one species do not necessarily apply to the others. Some of the tools available for genetic manipulation that have been developed along with these studies are also described. Two of them are of particular interest in this postgenomic period: inducible systems to express foreign genes and specific inhibition of gene expression by RNA interference

Antigenic variation at the surface of infected erythrocytes in plasmodium falciparum

Os membros da família dos genes var de Plasmodium falciparum codificam para receptores que desempenham um papel importante na patogenicidade da malária. O mecanismo responsável pela seleçäo da expressäo dos diferentes membros da família dos genes var ("switching") tem sido estdado utilizando populações de parasitas clonados, selecionados por suas características adesivas. O parasita expressa um único gene var o estágio de trofozoíto do seu ciclo de vida. Análises dos sítios de expressäo, ativos ou inativos, dos genes var demonstraram que o controle da expressäo ocorre durante a transcriçäo e a ativaçäo destes genes ocorre "in situ". Observamos que näo há sobreposiçäo no repertório dos genes var para diferentes isolados de laboratório, sugerindo desta maneira a existência de mecanismos para a geraçäo de diversidade desta família gênica. Experimentos de "fluorescence in situ hybridization" (FISH) mostraram que as extremidades dos cromossomos de P. falciparum estäo fisicamente associados e que esta formaçäo é importante para a geraçäo da diversidade dos genes var.

Nucleotide sequences of the VP1 capsid proteins of wild poliovirus types 1 and 3 from epidemic areas of Brazil

The nucleotide sequences encoding the capsid protein VP1 were determined for the wild polioviruses of serotypes 1 and 3 endemic to the northeastern region of Brazil. Compared with the corresponding Sabin vaccine strain sequences, the wild isolates differed at 20%(type 1) and 22%(type 3) of their nucleotide positions, and in 7%(type 1) and 11%(type 3) of their amino acid residues. The highest degree of amino acid heterogeneity occurred within the amino-terminal residues of the VP1 proteins. Intratypic amino acid differences also occurred in VP1 surface residues that form parts of antigenic sites for neutralizing antibodies