12.04.2015 Уважаемые друзья, коллеги и гости сайта! На сайте журнала "Infection, genetics and evolution" опубликована наша новая статья об открытии явления межвидовой гибридизации между иксодовыми клещами Ixodes persulcatus и I. pavlovskyi в зоне их симпатрии на территории Западной Сибири (Томская область).
Kovalev S.Y., Mikhaylishcheva M. S., Mukhacheva T.A.
Natural hybridization of the ticks Ixodes persulcatus and Ixodes pavlovskyi in their sympatric populations in Western Siberia // Infection, Genetics and Evolution. 2015. - V.32. - p. 388–395 Article first published online: 11 APR 2015. DOI: 10.1016/j.meegid.2015.04.003
Abstract
Hybridization of ticks of the genus Ixodes has been described for several species under laboratory conditions although no molecular genetics evidence confirming interspecific hybridization in nature is available. We have designed a real time PCR targeted on nuclear (ITS2) and mitochondrial (cox1) markers to accurately identify tick species and to detect interspecific hybrids of I. persulcatus and I. pavlovskyi in their sympatric populations in Western Siberia. A survey of 783 individual ticks from a suburb of Tomsk showed that 44.2% of ticks belong to I. pavlovskyi species and 55.8% to I. persulcatus, based on the mtDNA data. Results obtained with the nuclear marker were not consistent, indicating that approximately 10% of the ticks were hybrids and about 5% revealed mtDNA introgression. Both hybridization and introgression have been shown to occur bidirectionally but more efficiently in the mating pair female I. pavlovskyi x male I. persulcatus than vice versa. The existence of the first generation hybrids and backcrosses challenges the existing view about effective reproductive barriers between I. pavlovskyi and I. persulcatus. While using only mitochondrial markers can lead to errors in determining tick species, we propose to use nuclear or both markers instead. The results obtained in the present paper and published earlier suggest that hybridization between closely related tick species in their sympatric zones is common rather than exceptional. The role of hybrid populations of vectors in the evolution of transmitted pathogens is also discussed.
17.02.2015 Уважаемые друзья, коллеги и гости сайта! Мы давно не обновляли новостную ленту нашего сайта - было много экспериментальной работы и не только. Но сегодня у нас есть хорошая новость. На сайте журнала "Infection, genetics and evolution"опубликована наша новая статья о филогеографической изменчивости Borrelia miyamotoi.
Tatyana A. Mukhacheva, Irina I. Salikhova, Sergey Y. Kovalev
Multilocus spacer analysis revealed highly homogeneous genetic background of Asian type of Borrelia miyamotoi // Infection, genetics and evolution. Article first published online: 7 Feb 2015, doi:10.1016/j.meegid.2015.02.009
Abstract
Borrelia miyamotoi, a member of the relapsing fever group borreliae, was first isolated in Japan and subsequently found in Ixodes ticks in North America, Europe and Russia. Currently, there are three types of B. miyamotoi: Asian or Siberian (transmitted mainly by Ixodes persulcatus), European (I. ricinus) and American (I. scapularis and I. pacificus). Despite the great genetic distances between B. miyamotoi types, isolates within a type are characterized by an extremely low genetic variability. In particular, strains of B. miyamotoi of Asian type, isolated in Russia from the Baltic sea to the Far East, have been shown to be identical based on the analysis of several conventional genetic markers, such as 16S rRNA, flagellin, outer membrane protein p66 and glpQ genes. Thus, protein or rRNA – coding genes were shown not to be informative enough in studying genetic diversity of B. miyamotoi within a type. In the present paper, we have attempted to design a new multilocus technique based on eight non-coding intergenic spacers (3686 bp in total) and have applied it to the analysis of intra-type genetic variability of В. miyamotoi detected in different regions of Russia and from two tick species, I. persulcatus and I. pavlovskyi. However, even though potentially the most variable loci were selected, no genetic variability between studied DNA samples was found, except for one nucleotide substitution in two of them. The sequences obtained were identical to those of the reference strain FR64b. Analysis of the data obtained with the GenBank sequences indicates a highly homogeneous genetic background of B. miyamotoi from the Baltic Sea to the Japanese Islands. In this paper, a hypothesis of clonal expansion of B. miyamotoi is discussed, as well as possible mechanisms for the rapid dissemination of one B. miyamotoi clone over large distances.
23.10.2014 Уважаемые друзья, коллеги и гости сайта! На сайте журнала "Ecology and evolution" появилась наша важнейшая статья которую мы готовили почти 2 года. В ней мы подвели итоги использования кластеронного подхода для изучения закономерностей изменчивости, механизмов распространения и эволюции ВКЭ.
Kovalev S.Y., Mukhacheva T.A. Tick-borne encephalitis virus subtypes emerged through rapid vector switches rather than gradual evolution // Ecology and Evolution, Article first published online: 23 OCT 2014, DOI: 10.1002/ece3.1301
Abstract
Tick-borne encephalitis is the most important human arthropod-borne virus disease in Europe and Russia, with an annual incidence of about 13 thousand people. Tick-borne encephalitis virus (TBEV) is distributed in the natural foci of forest and taiga zones of Eurasia, from the Pacific to the Atlantic coast. Currently, there are three mutually exclusive hypotheses about the origin and distribution of TBEV subtypes, although they are based on the same assumption of gradual evolution. Recently, we have described the structure of TBEV populations in terms of a clusteron approach, a clusteron being a structural unit of viral population [Kovalev and Mukhacheva (2013) Infect. Genet. Evol., 14, 22–28]. This approach allowed us to investigate questions of TBEV evolution in a new way and to propose a hypothesis of quantum evolution due to a vector switch. We also consider a possible mechanism for this switch occurring in interspecific hybrids of ticks. It is necessarily accompanied by a rapid accumulation of mutations in the virus genome, which is contrary to the generally accepted view of gradual evolution in assessing the ages of TBEV populations. The proposed hypothesis could explain and predict not only the formation of new subtypes, but also the emergence of new vector-borne viruses.
07.08.2014 Уважаемые друзья, коллеги и гости сайта! Сообщаем Вам, что сегодня была опубликована электронная версия нашей новой статьи, посвященной изучению популяционной структуры боррелий, на основе дифференциации геновидов боррелий методом ПЦР в реальном времени. С текстом можно ознакомиться по ссылке ниже:
T.A. Mukhacheva, S.Y. Kovalev Borrelia spirochetes in Russia: Genospecies differentiation by real-time PCR Ticks Tick-borne Dis. - 2014. Article first published online: 07 Aug 2014 DOI: http://dx.doi.org/10.1016/j.ttbdis.2014.05.016
Abstract
Spirochetes of the Borrelia burgdorferi sensu lato complex are the causative agent of Lyme borreliosis which is widespread in Russia. Nowadays, three clinically important B. burgdorferi s.l. genospecies, B. afzelii, B. garinii, B. bavariensis sp. nov., can be found in Russia, as well as B. miyamotoi, which belongs to the tick-borne relapsing fever group of spirochetes. Several techniques have been developed to differentiate Borrelia genospecies. However, most of them do not allow detection of all of these genospecies simultaneously. Also, no method based on the RT-PCR TaqMan approach has been proposed to differentiate the genetically closely related species B. bavariensis and B. garinii. In the present paper, we investigated two species of ticks, I. persulcatus and I. pavlovskyi (1343 and 92 adults, respectively). Two sets of primers and probes for RT-PCR, with uvrA, glpQ and nifS genes as targets, were designed to detect four Borrelia genospecies in positive samples. The average prevalence of Borreliasp. was about 40%, with B. afzelii as the most prevalent genospecies. Mixed infections of B. bavariensisand B. garinii were found to be extremely rare. While B. bavariensis was predominant in I. persulcatus, I. pavlovskyi ticks were infected exclusively by B. garinii. The proposed technique proved to be efficient in selection of individual Borrelia species for further genetic analysis, in particular, for multilocus sequence typing. Also, it could be applied for the differentiation of Borrelia genospecies in clinical material.
18.04.2014 Наступает время активности иксодовых клещей. Лаборатория молекулярной генетики УрФУ приглашает научно-исследовательские организации, областные Центры Роспотребнадзора, а также всех заинтересованых лиц к сотрудничеству в области изучения молекулярной эпидемиологии клещевого энцефалита и лайм-боррелиоза. Мы предлагаем на взаимовыгодной основе провести исследования на предмет зараженности клещей возбудителями этих природно-очаговых инфекций. Нас интересуют практически все территории РФ. Полученные результаты внесут существенный вклад в понимание процессов происхождения, распространения и поддержания природных очагов, а также выяснения особенностей эволюции возбудителей. Обращайтесь!!!
29.01.2014 Поздравляем Мухачеву Татьяну с победой в конкурсе "Лучший молодой ученый" 2013 года и вручением Диплома Лауреата премии Губернатора Свердловской области "За лучшую работу в области общей биологии"! Награждение состоялось 29 января в Демидовском зале УрФУ.
27.12.2013 Уважаемые друзья, коллеги и гости сайта! Лаборатория Молекулярной генетики поздравляет с Наступающим Новым Годом! Процветания, творческих успехов, а главное здоровья в 2014! Пусть сбудутся ваши мечты и реализуются намеченные планы!!!
