And using CSV and DataFrames:
julia> using DataFrames, CSV
julia> df = CSV.read("MyFile_Horizontal.txt", DataFrame, header=[:a, :b, :c, :d])
1×4 DataFrame
│ Row │ a │ b │ c │ d │
│ │ Int64 │ Int64 │ Float64 │ Int64 │
├─────┼───────┼─────────┼─────────┼───────┤
│ 1 │ 5 │ 2450000 │ 5.67e-8 │ 1 │
julia> CSV.write("delim_file.txt", df, header=false)
"delim_file.txt"
shell> cat delim_file.txt
5,2450000,5.67e-8,1
You can also call CSV.read with header=false to let it choose column names.
Edit: I forgot about storing the DataFrame values in individual variables:
julia> a,b,c,d = df[1,:];
julia> CSV.write("delim_file.txt", Tables.table([a b c d]), header=false)
"delim_file.txt"
shell> cat delim_file.txt
5.0,2.45e6,5.67e-8,1.0
but for just a few variables from a single line of text I would rather stay with DelimitedFiles.