Different mechanisms regulate productive herpes simplex virus 1 (HSV-1) and HSV-2 infections in adult trigeminal neurons

Abstract

Herpes simplex virus 1 (HSV-1) and HSV-2 establish latency in different neuronal subtypes (A5+ and KH10+) in murine trigeminal ganglia, results which correlate with restricted productive infection in these neurons in vitro. HSV-2 latency-associated transcript (LAT) contains a cis-acting regulatory element near the transcription start site that promotes productive infection in A5+ neurons and a second element in exon 1 that inhibits productive infection in KH10+ neurons. HSV-1 contains no such regulatory sequences, demonstrating different mechanisms for regulating productive HSV infection in neurons.

Fig 1

Productive infection of cultured primary adult murine TG neurons with HSV-2 LAT region deletion and chimeric viruses (multiplicity of infection [MOI], 30; 10 h postinoculation). (A) Percentages of total (hatched bars), A5+ (black bars), and KH10+ (gray bars) neurons productively infected with HSV-1 and HSV-2, as identified by MAbs A5 and KH10, and polyclonal antisera against HSV-1 or HSV-2. (These data were published previously [3] and are shown here for reference). (B) Percentages of A5+ and KH10+ neurons productively infected with HSV-2 wild type (333) and HSV-2 LAT region deletion viruses (dLAT and LAP2). (C) Percentages of A5+ and KH10+ neurons productively infected with HSV-2 wild type (333), chimeric virus HSV2/LAT1, and its rescuant, HSV2/LAT1-R. (D) Maps illustrating HSV-2 LAT region deletion and chimeric sequence swap. Deletions are indicated by white boxes on the HSV-2 LAT region (black), and the HSV-1 sequence placed into HSV-2 is indicated by a hatched box on the HSV-2 background (black). ICP0 transcript is shown for reference.

Fig 2

Productive infection of cultured primary adult murine TG neurons with HSV-1 LAT region deletion and chimeric viruses (MOI, 30; 10 h postinoculation). (A) Percentages of A5+ and KH10+ neurons productively infected with HSV-1 wild-type (McKrae, KOS, 17+) and HSV-1 LAT region deletion (McKrae 2903, KOS/62, 17dPst, 17dSty, 17d348) viruses. (B) Percentages of A5+ and KH10+ neurons productively infected with HSV-1, chimeric virus HSV1/LAT2, or HSV2-GFP or coinfected with both HSV1/LAT2 and HSV2-GFP, evaluated for productive infection using polyclonal antisera to detect HSV-1 and HSV1/LAT2 and GFP expression to detect HSV2-GFP. (C) Maps illustrating HSV-1 LAT region deletions and chimeric sequence swap. Deletions are indicated by white boxes, and beta-galactosidase is indicated by a gray box on the HSV-1 LAT region (hatched); HSV-2 sequence placed into HSV-1 is indicated by a black box on the HSV-1 background (hatched). ICP0 transcript is shown for reference.

Fig 3

Productive infection of cultured primary adult murine TG neurons with HSV-2, the chimeric viruses P1, S1, and E1, and the E1 rescuant (MOI, 30; 10 h postinoculation). (A) Percentages of A5+ and KH10+ neurons productively infected with HSV-2 (333), the chimeric viruses P1, S1, and E1, and the E1 rescuant E1-R. (B) Maps illustrating LAT region chimeric sequence swaps. HSV-1 LAT sequences (hatched) replaced HSV-2 LAT sequences (black). P1 contains the HSV-1 LAT promoter from NotI to the PvuI site just downstream of the TATA box (the 5′ end of the region replaced in HSV2/LAT1); S1 contains the HSV-1 LAT sequence from the PvuI site through ∼1.5 kb downstream of the 5′ splice site of the intron (the 3′ end of the region replaced in HSV2/LAT1) but excludes ICP0 coding sequences; E1 contains HSV-1 LAT exon 1 from the TATA box to the 5′ splice site of the intron. ICP0 transcript is shown for reference.

Fig 4

Alignment of HSV-1, HSV-2, and chimeric viruses. Sequences of HSV-1, HSV-2, HSV1/LAT2, HSV2/LAT1, P1, S1, and E1 are aligned at the TATA box and the PvuI restriction enzyme site just downstream (gray boxes). HSV-1 sequences are bold, and HSV-2 sequences are normal font. Arrows indicate LAT transcription start sites. Underlined sequences are HSV-2 sequences present in wild-type HSV-2, HSV1/LAT2, and S1; this sequence is necessary for productive infection in A5+ neurons.