diff --git a/phylogenetic/Snakefile b/phylogenetic/Snakefile
index 622ba18..03d717d 100644
--- a/phylogenetic/Snakefile
+++ b/phylogenetic/Snakefile
@@ -4,8 +4,8 @@ rule all:
     input:
         auspice_json = "auspice/zika.json"
 
-include: "rules/prepare_sequences.smk"
 include: "rules/merge_sequences_usvi.smk"
+include: "rules/prepare_sequences.smk"
 include: "rules/construct_phylogeny.smk"
 include: "rules/annotate_phylogeny.smk"
 include: "rules/export.smk"
diff --git a/phylogenetic/defaults/config_zika.yaml b/phylogenetic/defaults/config_zika.yaml
index a3627fb..ddaf039 100644
--- a/phylogenetic/defaults/config_zika.yaml
+++ b/phylogenetic/defaults/config_zika.yaml
@@ -1,7 +1,15 @@
 # Sequences must be FASTA and metadata must be TSV
 # Both files must be zstd compressed
-sequences_url: "https://data.nextstrain.org/files/workflows/zika/sequences.fasta.zst"
-metadata_url: "https://data.nextstrain.org/files/workflows/zika/metadata.tsv.zst"
+
+inputs:
+  - name: ncbi
+    metadata: "s3://nextstrain-data/files/workflows/zika/metadata.tsv.zst"
+    sequences: "s3://nextstrain-data/files/workflows/zika/sequences.fasta.zst"
+
+additional_inputs:
+  - name: usvi
+    metadata: "data/metadata_usvi.tsv"
+    sequences: "data/sequences_usvi.fasta"
 
 strain_id_field: "accession"
 
diff --git a/phylogenetic/rules/annotate_phylogeny.smk b/phylogenetic/rules/annotate_phylogeny.smk
index d09daf7..1de8bef 100644
--- a/phylogenetic/rules/annotate_phylogeny.smk
+++ b/phylogenetic/rules/annotate_phylogeny.smk
@@ -73,7 +73,7 @@ rule traits:
     """
     input:
         tree = "results/tree.nwk",
-        metadata = "data/metadata_all.tsv"
+        metadata = input_metadata,
     output:
         node_data = "results/traits.json",
     params:
diff --git a/phylogenetic/rules/construct_phylogeny.smk b/phylogenetic/rules/construct_phylogeny.smk
index 3393ce0..b143d76 100644
--- a/phylogenetic/rules/construct_phylogeny.smk
+++ b/phylogenetic/rules/construct_phylogeny.smk
@@ -43,7 +43,7 @@ rule refine:
     input:
         tree = "results/tree_raw.nwk",
         alignment = "results/aligned.fasta",
-        metadata = "data/metadata_all.tsv"
+        metadata = input_metadata,
     output:
         tree = "results/tree.nwk",
         node_data = "results/branch_lengths.json"
diff --git a/phylogenetic/rules/export.smk b/phylogenetic/rules/export.smk
index 77d020f..f09870b 100644
--- a/phylogenetic/rules/export.smk
+++ b/phylogenetic/rules/export.smk
@@ -29,7 +29,7 @@ rule export:
     """Exporting data files for for auspice"""
     input:
         tree = "results/tree.nwk",
-        metadata = "data/metadata_all.tsv",
+        metadata = input_metadata,
         branch_lengths = "results/branch_lengths.json",
         traits = "results/traits.json",
         nt_muts = "results/nt_muts.json",
diff --git a/phylogenetic/rules/merge_sequences_usvi.smk b/phylogenetic/rules/merge_sequences_usvi.smk
index 3765937..7ee0c7f 100644
--- a/phylogenetic/rules/merge_sequences_usvi.smk
+++ b/phylogenetic/rules/merge_sequences_usvi.smk
@@ -21,22 +21,141 @@ This part of the workflow usually includes the following steps:
 
 """
 
-rule append_usvi:
-    """Appending USVI sequences"""
-    input:
-        sequences = "data/sequences.fasta",
-        metadata = "data/metadata.tsv",
-        usvi_sequences = "data/sequences_usvi.fasta",
-        usvi_metadata = "data/metadata_usvi.tsv"
+# ------------- helper functions to collect, merge & download input files ------------------- #
+NEXTSTRAIN_PUBLIC_BUCKET = "s3://nextstrain-data/"
+
+def _parse_config_input(input):
+    """
+    Parses information from an individual config-defined input, i.e. an element within `config.inputs` or `config.additional_inputs`
+    and returns information snakemake rules can use to obtain the underlying data.
+
+    The structure of `input` is a dictionary with keys:
+    - name:string (required)
+    - metadata:string (optional) - a s3 URI or a local file path
+    - sequences:string|dict[string,string] (optional) - either a s3 URI or a local file path, in which case
+      it must include a '{segment}' wildcard substring, or a dict of segment → s3 URI or local file path,
+      in which case it must not include the wildcard substring.
+
+    Returns a dictionary with optional keys:
+    - metadata:string - the relative path to the metadata file. If the original data was remote then this represents
+      the output of a rule which downloads the file
+    - metadata_location:string - the URI for the remote file if applicable else `None`
+    - sequences:function. Takes in wildcards and returns the relative path to the sequences FASTA for the provided
+      segment wildcard, or returns `None` if this input doesn't define sequences for the provided segment.
+    - sequences_location:function. Takes in wildcards and returns the URI for the remote file, or `None`, where applicable.
+
+    Raises InvalidConfigError
+    """
+    name = input['name']
+    lambda_none = lambda w: None
+
+    info = {'metadata': None, 'metadata_location': None, 'sequences': lambda_none, 'sequences_location': lambda_none}
+
+    def _source(uri, *,  s3, local):
+        if uri.startswith('s3://'):
+            return s3
+        elif uri.lower().startswith('http://') or uri.lower().startswith('https://'):
+            raise InvalidConfigError("Workflow cannot yet handle HTTP[S] inputs")
+        return local
+
+    if location:=input.get('metadata', False):
+        info['metadata'] = _source(location,  s3=f"data/{name}/metadata.tsv", local=location)
+        info['metadata_location'] = _source(location,  s3=location, local=None)
+
+    if location:=input.get('sequences', False):
+        info['sequences'] = _source(location,  s3=f"data/{name}/sequences.fasta", local=location)
+        info['sequences_location'] = _source(location,  s3=location, local=None)
+
+    return info
+
+
+def _gather_inputs():
+    all_inputs = [*config['inputs'], *config.get('additional_inputs', [])]
+
+    if len(all_inputs)==0:
+        raise InvalidConfigError("Config must define at least one element in config.inputs or config.additional_inputs lists")
+    if not all([isinstance(i, dict) for i in all_inputs]):
+        raise InvalidConfigError("All of the elements in config.inputs and config.additional_inputs lists must be dictionaries"
+            "If you've used a command line '--config' double check your quoting.")
+    if len({i['name'] for i in all_inputs})!=len(all_inputs):
+        raise InvalidConfigError("Names of inputs (config.inputs and config.additional_inputs) must be unique")
+    if not all(['name' in i and ('sequences' in i or 'metadata' in i) for i in all_inputs]):
+        raise InvalidConfigError("Each input (config.inputs and config.additional_inputs) must have a 'name' and 'metadata' and/or 'sequences'")
+
+    return {i['name']: _parse_config_input(i) for i in all_inputs}
+
+input_sources = _gather_inputs()
+
+def input_metadata(wildcards):
+    inputs = [info['metadata'] for info in input_sources.values() if info.get('metadata', None)]
+    return inputs[0] if len(inputs)==1 else "results/metadata_merged.tsv"
+
+def input_sequences(wildcards):
+    inputs = [info['sequences'] for info in input_sources.values() if info.get('sequences', None)]
+    return inputs[0] if len(inputs)==1 else "results/sequences_merged.fasta"
+
+# def input_sequences(wildcards):
+#     inputs = list(filter(None, [info['sequences'](wildcards) for info in input_sources.values() if info.get('sequences', None)]))
+#     return inputs[0] if len(inputs)==1 else "results/sequences_merged_{segment}.fasta"
+
+rule download_s3_sequences:
     output:
-        sequences = "data/sequences_all.fasta",
-        metadata = "data/metadata_all.tsv"
+        sequences = "data/{input_name}/sequences.fasta",
+    params:
+        address = lambda w: input_sources[w.input_name]['sequences_location'],
+        no_sign_request=lambda w: "--no-sign-request" \
+            if input_sources[w.input_name]['sequences_location'].startswith(NEXTSTRAIN_PUBLIC_BUCKET) \
+            else "",
     shell:
         """
-        seqkit rmdup {input.usvi_sequences} {input.sequences} > {output.sequences}
+        aws s3 cp {params.no_sign_request:q} {params.address:q} - | zstd -d > {output.sequences}
+        """
 
+rule download_s3_metadata:
+    output:
+        metadata = "data/{input_name}/metadata.tsv",
+    params:
+        address = lambda w: input_sources[w.input_name]['metadata_location'],
+        no_sign_request=lambda w: "--no-sign-request" \
+            if input_sources[w.input_name]['metadata_location'].startswith(NEXTSTRAIN_PUBLIC_BUCKET) \
+            else "",
+    shell:
+        """
+        aws s3 cp {params.no_sign_request:q} {params.address:q} - | zstd -d > {output.metadata}
+        """
+
+rule merge_metadata:
+    """
+    This rule should only be invoked if there are multiple defined metadata inputs
+    (config.inputs + config.additional_inputs)
+    """
+    input:
+        **{name: info['metadata'] for name,info in input_sources.items() if info.get('metadata', None)}
+    params:
+        metadata = lambda w, input: list(map("=".join, input.items())),
+        id_field = config['strain_id_field'],
+    output:
+        metadata = "results/metadata_merged.tsv"
+    shell:
+        r"""
         augur merge \
-          --metadata ingest={input.metadata} usvi={input.usvi_metadata} \
-          --metadata-id-columns accession \
-          --output-metadata {output.metadata}
-        """
\ No newline at end of file
+            --metadata {params.metadata:q} \
+            --metadata-id-columns {params.id_field} \
+            --output-metadata {output.metadata}
+        """
+
+rule merge_sequences:
+    """
+    This rule should only be invoked if there are multiple defined sequences inputs
+    (config.inputs + config.additional_inputs) for this particular segment
+    """
+    input:
+        **{name: info['sequences'] for name,info in input_sources.items() if info.get('sequences', None)}
+    output:
+        sequences = "results/sequences_merged.fasta"
+    shell:
+        r"""
+        seqkit rmdup {input:q} > {output.sequences:q}
+        """
+
+# -------------------------------------------------------------------------------------------- #
\ No newline at end of file
diff --git a/phylogenetic/rules/prepare_sequences.smk b/phylogenetic/rules/prepare_sequences.smk
index 39bd66f..a6f455c 100644
--- a/phylogenetic/rules/prepare_sequences.smk
+++ b/phylogenetic/rules/prepare_sequences.smk
@@ -21,34 +21,6 @@ This part of the workflow usually includes the following steps:
 See Augur's usage docs for these commands for more details.
 """
 
-rule download:
-    """Downloading sequences and metadata from data.nextstrain.org"""
-    output:
-        sequences = "data/sequences.fasta.zst",
-        metadata = "data/metadata.tsv.zst"
-    params:
-        sequences_url = config["sequences_url"],
-        metadata_url = config["metadata_url"],
-    shell:
-        """
-        curl -fsSL --compressed {params.sequences_url:q} --output {output.sequences}
-        curl -fsSL --compressed {params.metadata_url:q} --output {output.metadata}
-        """
-
-rule decompress:
-    """Decompressing sequences and metadata"""
-    input:
-        sequences = "data/sequences.fasta.zst",
-        metadata = "data/metadata.tsv.zst"
-    output:
-        sequences = "data/sequences.fasta",
-        metadata = "data/metadata.tsv"
-    shell:
-        """
-        zstd -d -c {input.sequences} > {output.sequences}
-        zstd -d -c {input.metadata} > {output.metadata}
-        """
-
 rule filter:
     """
     Filtering to
@@ -58,8 +30,8 @@ rule filter:
       - minimum genome length of {params.min_length} (50% of Zika virus genome)
     """
     input:
-        sequences = "data/sequences_all.fasta",
-        metadata = "data/metadata_all.tsv",
+        sequences = input_sequences,
+        metadata = input_metadata,
         exclude = "defaults/dropped_strains.txt",
     output:
         sequences = "results/filtered.fasta"