1574-C 24 DECEMBER 2021 • VOL 374 ISSUE 6575 science.org SCIENCE
RESEARCH | IN SCIENCE JOURNALS
suggesting that they emerged
to escape immune recognition.
Remodeling of the N-terminal
domain allows the variants to
escape recognition by most
neutralizing antibodies that tar-
get it. The work could guide the
development of next-generation
vaccines and antibody therapies.
—V V
Science, abl8506, this issue p. 1621
PEROVSKITE STRUCTURE
Stable but not quite cubic
The black, photoactive phase of
formamidinium (FA) perovskites,
which is usually stabilized by
cation alloying to avoid the
formation of inactive hexagonal
phases, is assumed to be cubic.
High-resolution microscopy
studies by Doherty et al. using
nanoscale probes revealed
that these FA-rich phases are
not cubic but rather undergo
slight tilting (by two degrees)
of the octahedra. Black phases
can have localized regions of
hexagonal phases that nucle-
ate degradation. Surface-bound
ethylenediaminetetraacetic acid
stabilized the tilted phase of pure
FA lead triiodide against environ-
mental degradation. —PDS
Science, abl4890, this issue p. 1598
CORONAVIRUS
A tool to probe
SARS-CoV-2 biology
To develop therapies against
severe acute respiratory
syndrome coronavirus 2 (SARS-
CoV-2) and emerging variants, it
is important to understand the
viral biology and the effect of
mutations. However, this is chal-
lenging because live virus can
only be studied in a few labora-
tories that meet stringent safety
standards. Syed et al. describe
a virus-like particle (VLP) that
comprises the four SARS-CoV-2
structural proteins, but instead
of packaging viral RNA, it pack-
ages messenger RNA (mRNA)
that expresses a reporter protein
(see the Perspective by Johnson
and Menachery). The amount of
reporter expressed in receiver
cells depends on the efficiency
of packaging and assembly
in the producer cells and the
efficiency of entry into receiver
cells. Mutations in the nucleo-
capsid protein that are found
in more transmissible variants
increase mRNA packaging and
expression. The VLPs provide a
platform for studying the effect
of mutations in the structural
proteins and for screening thera-
peutics. —VV
Science, abl6184, this issue p. 1626;
see also abn3781, p. 1557MUCOSAL IMMUNOLOGY
Stromal cells
in training immunity
Immune responses to pathogens
are heightened in individuals
previously exposed to patho-
gen-associated stimuli, a
phenomenon known as innate
immune training. This process is
accomplished through metabolic
reprogramming and epigenetic
changes, but the underlying
mechanisms are not fully under-
stood. Wu et al. investigated
the functional requirement
of interleukin (IL)-17 receptor
signaling in fibroblastic reticular
cells (FRCs) in the development
of protective antibody responses
against gut infection and studied
how innate immune training
affects these responses. Mild
gut inflammatory training before
bacterial infection enhanced gut-
protective antibody production
and reduced colon inflammation.
Inflammatory training required
IL-17 signaling in FRCs and IL-10
production by B cells. These
findings reveal a mechanism of
innate immune training in FRCs
for protection against gut infec-
tion. —HMI
Sci. Immunol. 6 , eaao3669 (2021).