Mutations in CypA Binding Region of HIV-1 Capsid Affect Capsid Stability and Viral Replication in Primary Macrophages

Mutations in the cyclophilin A (CypA) binding region in the HIV-1 capsid affect their dependency on the known HIV-1 cofactor CypA and allow escape from the HIV-1 restriction factor Trim5α in human and simian cells. Here we study the effect of these mutations in the CypA binding region of capsid on cofactor binding, capsid destabilization, and viral replication in primary cells. We showed that the viral capsid with mutations in the CypA binding region (CypA-BR) interacted efficiently with CypA, but had an increased stability upon infection as compared to the wild-type capsid. Interestingly, the wild-type virus was able to infect monocyte-derived macrophages (MDM) more efficiently as compared to the CypA-BR mutant variant. The lower infectivity of the CypA-BR mutant virus in MDM was associated with lower levels of reverse transcription products. Similar to the wild-type virus, the CypA-BR mutant variant was unable to induce a strong innate response in primary macrophages. These data demonstrate that mutations in the CypA binding site of the capsid resulted in higher capsid stability and hampered infectivity in macrophage

Migration of Vanadium in the Ecosystem of Kuchurgan Cooling Reservoir of the Moldovan Thermal Power Plant

В статье отражены результаты многолетних исследований динамики миграции ванадия в воде, донных отложениях, высшей водной растительности, донных беспозвоночных и рыбах водоема-охладителя Молдавской ГРЭС. Установлена четкая зависимость уровня ванадия в водной экосистеме от количества и состава сжигаемого на станции топлива. Миграция ванадия в системе вода – иловые отложения в большинстве случаев идет из водных слоев в донные отложения, но при интенсификации процессов сульфатредукции, гниения, при уменьшении концентрации растворенного кислорода возможна и обратная диффузия из илов в воду. Уровень накопления металлов в гидробионтах – один из важнейших показателей при биомониторинге металлов в водных экосистемах. Показано, что концентрация ванадия в водных растениях и животных определяется интенсивностью процессов метаболизма, межвидовыми особенностями, интенсивностью пластического и генеративного обмена (у рыб) и в то же время является отражением динамики ванадия в среде обитания. Коэффициент биологического накопления в водных организмах достигал величины n×107The article describes the results of long-term research on the dynamics of vanadium migration in water, bottom sediments, higher aquatic plants, bottom invertebrates, and fishes in the cooling reservoir of the Moldovan Thermal Power Plant. An obvious dependence of the level of vanadium in aquatic ecosystem on the quantity and composition of burnt fuel at the plant was established. In most of cases the migration of vanadium in the system “water – silts” occured from water layers to bottom sediments. But if the intensity of sulphate reduction and putrefaction processes increases and the concentration of dissolved oxygen decreases the reverse diffusion from silts to water will become possible. The level of accumulation of metals in hydrobionts is one of the most important parameters in the biomonitoring of metals in aquatic ecosystems. The concentration of vanadium in aquatic plants and animals depended on the intensity of metabolism and interspecific features, plastic and generative metabolism (at fish), but in the same time reflected the dynamics of vanadium in the environment. The values of the coefficient of vanadium biological accumulation in aquatic organisms reached up to n×10

A Polymorphism at Position 400 in the Connection Subdomain of HIV-1 Reverse Transcriptase Affects Sensitivity to NNRTIs and RNaseH Activity

<div><p>Reverse transcriptase (RT) plays an essential role in HIV-1 replication, and inhibition of this enzyme is a key component of HIV-treatment. However, the use of RT inhibitors can lead to the emergence of drug-resistant variants. Until recently, most clinically relevant resistance mutations were found in the polymerase domain of RT. Lately, an increasing number of resistance mutations has been identified in the connection and RNaseH domain. To further explore the role of these domains we analyzed the complete RT sequence of HIV-1 subtype B patients failing therapy. Position A/T400 in the connection subdomain is polymorphic, but the proportion of T400 increases from 41% in naïve patients to 72% in patients failing therapy. Previous studies suggested a role for threonine in conferring resistance to nucleoside RT inhibitors. Here we report that T400 also mediates resistance to non-nucleoside RT inhibitors. The susceptibility to NVP and EFV was reduced 5-fold and 2-fold, respectively, in the wild-type subtype B NL4.3 background. We show that substitution A400T reduces the RNaseH activity. The changes in enzyme activity are remarkable given the distance to both the polymerase and RNaseH active sites. Molecular dynamics simulations were performed, which provide a novel atomistic mechanism for the reduction in RNaseH activity induced by T400. Substitution A400T was found to change the conformation of the RNaseH primer grip region. Formation of an additional hydrogen bond between residue T400 and E396 may play a role in this structural change. The slower degradation of the viral RNA genome may provide more time for dissociation of the bound NNRTI from the stalled RT-template/primer complex, after which reverse transcription can resume.</p></div