Molecular epidemiological analysis of the origin and transmission dynamics of the hiv-1 crf01_ae sub-epidemic in Bulgaria

Ivailo Alexiev*, Ellsworth M. Campbell, Sergey Knyazev, Yi Pan, Lyubomira Grigorova, Reneta Dimitrova, Aleksandra Partsuneva, Anna Gancheva, Asya Kostadinova, Carole Seguin-Devaux, Ivaylo Elenkov, Nina Yancheva, William M. Switzer

*Corresponding author for this work

Research output: Contribution to journalArticleResearchpeer-review

8 Citations (Scopus)


HIV-1 subtype CRF01_AE is the second most predominant strain in Bulgaria, yet little is known about the molecular epidemiology of its origin and transmissibility. We used a phylodynamics approach to better understand this sub-epidemic by analyzing 270 HIV-1 polymerase (pol) sequences collected from persons diagnosed with HIV/AIDS between 1995 and 2019. Using network analyses at a 1.5% genetic distance threshold (d), we found a large 154-member outbreak cluster composed mostly of persons who inject drugs (PWID) that were predominantly men. At d = 0.5%, which was used to identify more recent transmission, the large cluster dissociated into three clusters of 18, 12, and 7 members, respectively, five dyads, and 107 singletons. Phylogenetic analysis of the Bulgarian sequences with publicly available global sequences showed that CRF01_AE likely originated from multiple Asian countries, with Vietnam as the likely source of the outbreak cluster between 1988 and 1990. Our findings indicate that CRF01_AE was introduced into Bulgaria multiple times since 1988, and infections then rapidly spread among PWID locally with bridging to other risk groups and countries. CRF01_AE continues to spread in Bulgaria as evidenced by the more recent large clusters identified at d = 0.5%, highlighting the importance of public health prevention efforts in the PWID communities.

Original languageEnglish
Article number116
Issue number1
Publication statusPublished - 16 Jan 2021


  • Circulat-ing recombinant forms
  • Drug resistance
  • HIV-1
  • Molecular epidemiology
  • Prevention
  • Transmission clusters
  • Transmission dynamics


Dive into the research topics of 'Molecular epidemiological analysis of the origin and transmission dynamics of the hiv-1 crf01_ae sub-epidemic in Bulgaria'. Together they form a unique fingerprint.

Cite this