Batai and Ngari viruses: M segment reassortment and association with severe febrile disease outbreaks in East Africa

Abstract

Ngari virus is an orthobunyavirus recently recognized as a reassortant between Bunyamwera virus and an as yet unidentified M segment donor. Analysis of M segment sequences of Batai and Ilesha viruses revealed 95% deduced amino acid identity between Batai virus and Ngari virus. These findings suggest Batai virus as the donor of Ngari virus M segment sequence. Analysis of Batai virus-related African isolates identified UgMP-6830, isolated from mosquitoes in Uganda, as an isolate of Batai virus. KV-141, isolated during a febrile disease outbreak in Sudan, was identified as another isolate of Ngari virus, emphasizing a role of this reassortant virus in severe human illness throughout East Africa.

FIG.1.

Analysis of M segment sequence conservation between BATV, NRIV, and ILEV. (A) Sliding-window distance analysis between BATV (MM2222) and NRIV (Kenya), ILEV, CVV, BUNV, Guaroa virus (GROV; GenBank accession no. AY380581), and California encephalitis virus (CEV; AF123483) (window, 60 amino acids [aa]; step 10 amino acids). (B) Alignment of terminal M segment sequences of BATV (MM2222), NRIV (Kenya), and ILEV. Coding sequence for the polyprotein is omitted, and only the ochre codon and initiation codon are indicated (underlined and overlined UUA and CAU, respectively; sequence given in genomic antisense orientation). Sequences used in PCR priming are indicated in lowercase italics.

FIG.1.

Analysis of M segment sequence conservation between BATV, NRIV, and ILEV. (A) Sliding-window distance analysis between BATV (MM2222) and NRIV (Kenya), ILEV, CVV, BUNV, Guaroa virus (GROV; GenBank accession no. AY380581), and California encephalitis virus (CEV; AF123483) (window, 60 amino acids [aa]; step 10 amino acids). (B) Alignment of terminal M segment sequences of BATV (MM2222), NRIV (Kenya), and ILEV. Coding sequence for the polyprotein is omitted, and only the ochre codon and initiation codon are indicated (underlined and overlined UUA and CAU, respectively; sequence given in genomic antisense orientation). Sequences used in PCR priming are indicated in lowercase italics.